Monthly Archives: January 2017

Borgundian Mechanized Infantry Loadout

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Let’s get this started. I’m following my own challenge rules, which you can find here. We’ve made a bunch of decisions so far, so let’s get those out of the way. Oh, and all weights are going to be in pounds, because I’m an American. Divide by 2.2 to get weights in commie kilos.

Carbine: HK 416. I didn’t specify a barrel length preference then, but we’ll go with 14.5 inches. Comes to 7.69 lbs empty. We’ll also need ammo in that gun. Thirty rounds of 62 grain M855A1 or similar in an aluminum, 30 round magazine comes to 1.06 lbs. Per doctrine, we’ll need a suppressor and an optic. We’ll take an Aimpoint Comp M4 red dot (0.74 lbs with mount and killflash) and a Surefire 556RC2 suppressor (1.06 lbs.). Also, we’ll need an IR laser/illuminator, because battles don’t stop at night. My choice there would be the B.E. Meyers MAWL-DA. I don’t have a weight for this, so I’m going to guesstimate 0.5 lbs based on other, similar devices. Plus a sling, which is going to set us back about another quarter pound. All of that adds up to 11.3 lbs, which is kinda sucky, actually. Oh well. Lots of capability there, not much to be done about it. Quit complaining and drop and give me thirty.

Armor time. See here for why I picked what I picked. IOTV (and we’ll add the deltoid (fragmentation) protectors, but not the side plates) is 26.69 lbs for a size medium. Size medium ECH is three pounds. Ballistic Eyewear adds 0.15 lbs, foam earplugs add 0.1 lbs, and knee and elbow pads add another 0.4 lbs. An FM50 gas mask rounds out the protective equipment list, adding another 1.85 lbs. Total weight for protective gear is 32.19 lbs.

Ammo. Pretty straightforward. Six spare thirty round magazines. Two M67 frag grenades. And two smoke grenades. Something like the M18, but with added thermal obscurants. Six mags comes to 6.36 lbs, two M67s comes to 1.76 lbs, and two M18s comes to 2.38 lbs, for a total ammo load of 10.5 lbs. Which doesn’t seem like a lot, but remember the vehicle holds more.

On to comestibles. I’ll go into more detail on this elsewhere. Since these are mechanized infantrymen, they have a big armored vehicle to move them around and carry stuff like food and water in reasonable quantities. Only the essentials need to be carried. For the standard, temperate European operating environment, we think two liters of water is an adequate amount to carry on the person, and we can top this off as needed from the vehicle stores or resupply. For food, we really only expect the soldier to carry an iron ration with him. This will take the form of something like the US military’s First Strike Ration, which is a hot-pocket-like sandwich that supplies the calorie and nutritional needs for one battle day. A full two-liter camelbak-type1 bladder is 4.88 lbs, and a First Strike Ration is 1.95 lbs, bringing total comestible weight to 6.83 lbs.

There are a few other items we need to list out. There’s the IFAK, the Individual First Aid Kit. This is for two reasons. First, it means a soldier can perform some first aid on his buddy. Second, a medic can always find some basic supplies (tourniquet, pressure bandage, sterile gloves) when he needs them in a pinch. Add a pound. We also need to issue a knife. For knife fighting duties, I’d like a double-edged knife, like the Gerber Mk. II. However, most knife tasks are utility tasks for the modern soldier. For these, a tough single-edge knife will work better. Something like a Ka-Bar. Tough, effective, legendary. I have one and love it. Add another 1.23 lbs for a Ka-bar and sheath. And we’ll need some night vision kit. I’ve been going for the high-end, feature-rich stuff. No sense in stopping now. We’ll take the PSQ-20B, which gives us third generation image intensifying optics plus thermal optics in one rugged, two pound unit. At least the battery pack is detachable and can be affixed to the back of the helmet for balance. Finally, we’ll need a radio. The PRC-159 from Harris should do nicely. Compatible with the once and future frequencies, plenty of encryption, good battery life. With battery, it weighs 1.72 lbs.

Almost done, I swear. The standard poncho with liner is a really great piece of kit. It’s waterproof, surprisingly warm, and extremely packable. That’s my one concession to weather that might crop up unexpectedly. Obviously, coats are worn when you can expect bad weather, like say in the winter. 1.5 lbs for the poncho and liner. And we’ll add a multitool, because they are ridiculously useful little things. 0.6 lbs for that.

Let’s wrap up by looking at what we’re not issuing. Recall that this is a regular rifleman. He is not a squad leader. Therefore, he does not usually need navigation equipment so he does not have a lensatic compass, maps, or a portable GPS receiver as a matter of course. He might be given these things as part of a specific mission, and that’s fine. Spare batteries for the various electronic devices mentioned are carried aboard the vehicle normally. As a side note, just about all the devices here take AA batteries. Logistical commonality strikes again!2 Similarly, cleaning kits are generally expected to be carried aboard the vehicle. as are entrenching tools. Further, since they aren’t on soldier’s backs, we can issue full size picks and spades, not the lame folding versions.

All-up weight for our kit is 68.87 lbs. Which is on the heavy side, but about on par with other modern armies. Remember, the pack is normally left in the vehicle, so it’s not counted in the fighting load.

1.) I actually prefer the Source brand bladders.
2.) Did you expect anything different from me?

Cargo Helicopter for Borgundy

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Between the two of us, Fishbreath is the clear rotorhead. And that’s fine. He really likes flying helicopters in sims.

I, on the other hand, am coming at this from the logistican’s perspective. I’m looking for a helicopter to haul stuff. It should be cheap. It should be reasonably modern. It should be readily available in numbers. Armored thrusts need lots of fuel, ammo, and food, and we need ways to get that materiel to the front. Let’s look at some big, ugly cargo helicopters. They’re probably no fun to fly, but they’re important just the same.

The most obvious choice would be the Mi-26. The biggest helicopter in mass production. Of course, being Russian, lower initial purchasing price comes with higher maintenance costs. That’s not a big dealbreaker though. Of greater concern is the revanchist Russian bear. Can they be depended on to supply spare parts in the future? The production line is also moderate. Besides, I’m sure Fishbreath is waiting to throw politics into this. Let’s dig deeper.

We come to that big, US Army classic: the CH-47F Chinook. It’s been in production since 1962. It can carry 55 men or just under 11 tonnes of cargo. Three machine guns can be mounted to cover soldiers. It maxes out at 170 knots. Plus, the price is reasonable. Not quite Russian cheap, but the service life is better, especially as far as engines are concerned.

Compared to other Western options, the Chinook is a real bargain. It’s almost one third of the cost of the big CH-53K, but carries two thirds the payload. Also, unlike the CH-53K, it’s in full-rate production now. It’s also a pretty common helicopter. This means spares are easy to come by, the secondary market can supplement our orders, and most importantly, that someone else (namely the U.S. Army) is on the hook for funding upgrades, not us.

There’s not much out of Europe that can lift as much as a Chinook can. The NH90 can’t (it’s more of an oversized Blackhawk), and it’s more expensive to boot. Plus, it’s been plagued with all manner of difficulties. Not that the Chinook hasn’t, but any such problems are long ago. Call me when the NH90 has been through several wars.

Like most modern helicopters, the Chinook has plenty of optional extras. High end digital controls built under common architecture principles are readily available, along with midair refueling equipment and modern composite rotors. There are three pintles (left, right, and rear exit doors) for mounting machine guns. It’s got a long, proven history of good service.

There’s not much more we could ask for in a cargo helicopter.

Hudson H9 Range Report

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I’ve got some data for you from Top Men in the field. First, here’s the design overview and analysis.

Range impressions were good. In general, people were happy with the trigger. It’s nice. Of course, it will take some getting used to, like any trigger (good or not). But they seem to have delivered on their design goal of “Crisp, 1911-like trigger” in a striker-fired design.

The gun is also very low recoil and very flat shooting. Our shooters really liked it. That’s another design objective accomplished.

Further things for the plus column: while the grips are not interchangeable with existing 1911 grip panels, Hudson has contracted VZ grips to make them. So options should be available pretty quick.

One other note, this likely a negative. The patent design shows a large number of small parts. So disassembly might be a royal pain. We can’t judge reliability from that, though, so don’t.

These sorts of range expos are not good for judging a pistol, but they can help build excitement and optimism. Check and check.

One more thing. Mags appear to be based on those for the S&W 5906. Which is a strange choice for magazines, as that pistol is no longer in production. It should keep some costs down though. And for all I know those get the grip angle they wanted better than other magazines.

Avidity Arms PD10

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More fun from SHOT. The Avidity Arms PD10 is another relatively new arrival. Avidity Arms is a small outfit, who have been working with Rob Pincus.

The PD10 is a roughly Glock 19 sized, single-stack 9mm pistol. It’s polymer framed. It uses 9mm 1911 magazines. On the one hand, this was almost certainly chosen to avoid magazine development and testing costs, so the final product could meet their target price point. Magazine development (like any part of pistol development) is expensive, and a single-stack, Glock 19 sized gun isn’t going to be in the running for any police or military contracts in the 21st century. Note that this does mean the grip is going to be somewhat longer than on a Glock 19, to accommodate a standard 1911 magazine.

It also raises some objections from me. I understand 9mm 1911 magazines are relatively common. But when you hear “9mm 1911”, you don’t think “paragon of reliability”. You probably think “unreliable”. Maybe “Jam-O-Matic”. 9mm 1911s have a well-deserved reputation for being difficult to get running right. The magazine is a part of this. I’m skeptical of using these in a pistol and getting a reliable result. Good 9mm 1911 magazines are also rather expensive, which bodes badly. Part of the problem with 1911 reliability is people buying cheap, crappy mags, discovering that they jam a lot, and blaming the platform. Ol’ Slabsides has a bunch of nostalgia value to back it up. This doesn’t. Also, with a 1911, you can at least buy a known good pistol while you mess around with magazines.

Problem two with 9mm 1911 magazines is that they tend to come in ‘full size’ lengths. Why is this a problem? Because that means you’re getting a ‘full size’ pistol. It’s a lot harder to scale a design down than it is to scale a design up. Want a bigger version of your pistol? That’s easy. A smaller version takes a lot more testing. I bring this up because small single-stack 9mms are selling really well right now. The M&P Shield, Walther PPS, and Glock 43 are all extremely popular. They’re all small. Considerably smaller than a G19 as far as length and height goes. For most of the gun-buying public1, I don’t really see the appeal here.

The PD10 seems to come with decent sights out of the box. They’re metal, at least. I don’t know what the sight picture looks like. The front dovetail is an M&P type, and the rear dovetail is a Glock type. I don’t know why this wasn’t designed to take M&P sights (front and rear dovetails) or Glock sights (front screw and rear dovetail). Picking a common sight mount is a good choice, but it really should be a common sight set.

And, of course, there are all the questions of reliability and company longevity that come with something new. Like I said with the Hudson H9, probably best to wait and see how this shakes out. In the meantime, the SiG P239 is a known reliable single stack 9mm pistol. Consider that if you’re in the market for a 9mm single stack that’s bigger than the M&P Shield.

1.) Fishbreath will be along in a moment to tell you about small-handed people who need pistols too.

Some Thoughts on the 1911

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I’m a big fan of the 1911 platform. There’s a lot right in that design. And they’re super fun to shoot. Let’s spend some time talking about what to consider if you’re looking to buy one.

The 1911 has some obvious shortcomings, like a single-stack magazine and its weight. There are handgun designs that carry bullets more efficiently today. However, the 1911 fits nearly every hand as a result of the narrow, single-stack magazine, points well, absorbs recoil well, and has an excellent trigger. They are fun to shoot.

As I put this together, the 1911 design has been around for 106 years. Splendid! That does, however, mean that things have changed a lot. The basics are the same, but we’re no longer sole-sourcing parts from Colt, and we’re no longer only trying to run US Army 230 grain ball ammo through it. Be aware.

Recall that the original design had a 5″ barrel, a steel frame, was chambered in .45 ACP, had relatively loose tolerances, and held seven (7) rounds in the flush-fitting magazine. The further you diverge from this, the more you hit tolerance stacking difficulties. So the more difficult it will be to get it running well.

Now, one could get a very fancy 1911, like my Springfield Professional. That’s an excellent choice, though not customisable at all. There are, of course, many other excellent places to get semi-custom (pick from a features list) or full custom (specify everything), though expect to pay a premium and wait. If you can find one configured to your liking, a bit more of a premium will let you skip the wait. These are very, very nice guns and you can be sure they’ll run well, even if you choose some bizarre configuration. Of course, this isn’t the only way to get a nice one.

There are lots of good guns from companies like Colt, Springfield Armory, Dan Wesson, etc. out there that will be cheaper than the semicustom builds, but still offering quality and desireable features. However, it is a little harder for one to choose a pistol in this price range. At the low end, you tend to get USGI-pattern clones from various foreign companies. There is little to differentiate those. At the high end, you cannot go wrong. Choose a smith or a company you like, spend some pleasant hours on the phone with them talking about your build, pay a large fee, and wait. You will be taken care of. But what about the rest?

Jeff Cooper commented that all you needed in a 1911 was sights you could see, a good trigger, and a dehorn job. We are not as minimalist as the great Colonel, but this is an excellent place to start. For sights, you ought to be sure they’re mounted with dovetails. Avoid the USGI-pattern mounts. Dovetails will let you a qualified gunsmith fit different sights should you wish something else. There is no one standard pattern of 1911 sight dovetails, so do your homework and see that your gun has a common one. It is easy enough to have the sights changed out to something you prefer if you can’t find a gun in your price range that has what you like, so long as you have done the rest. If you do not know your sight preference, it may be expensive to ascertain it. Personally, I would suggest a high visibility front post and a plain rear, with the rear notch rather wider than the front post. Add tritium if you insist. As with many things, your tastes may differ, and I shan’t bother to argue with you.

Triggers are very important. They are one of the reasons people still love 1911s. A well set up trigger will make you look good. There’s not much I can tell you, not being a hardcore pistolsmith. Most reasonably well put together 1911s will have a decent trigger. For a good, or better still, a great trigger, you will have to pay more. Fortunately, you get what you pay for. I would not obsess too much about the weight, so long as it isn’t ludicrously heavy. The short, crisp characteristics that are so easy to come by are far more important then whether your trigger measures four or five or howevermany pounds. I should also point out that modifying the trigger on a 1911 is most certainly not something that can be done by a talentless hack, like modifying the trigger on a Glock or M&P. If you want changes to the trigger characteristics of the 1911 you bought, see a proper 1911 specialist pistolsmith. This is not something for a guy with youtube, files, and a kitchen table.

A dehorn job is definitely nice to have, though I wouldn’t obsess over some of the slick guns out there. And I probably wouldn’t send a gun off, but that’s just me. Avoid guns with obvious snag points. This is as good a time as any to segue into feel. The feel of a 1911 is pretty important if you’re picking one. They all point the same (superbly). Some thought should be given to the grips, though these are quite simple to change out. Do not hesitate to do so. I would strongly suggest using flathead grip screws, as John Moses Browning intended. If they come loose, it is easy to tighten them back up in the field with the rim of a .45 ACP cartridge. To hell with “modern” hex, torx, or whateverx bits.

Personally, I’m also a big fan of checkering on the front and backstrap. Since the backstrap is the mainspring housing, it’s easy enough to change out if you don’t like the one you’ve got. You can add checkering/texture up front by sending to a gunsmith. At a cost of course. I think it’s easier to get this from the factory. A well-stocked gun store will have many examples for you to feel, but it is how they perform on the clock that counts, so find a rental desk if you can. As an example, Fishbreath complained quite a bit about the 20 lpi checkering on Dana1, until he got some range time. And then he understood and could appreciate the checkering. Though, he still might prefer something a trifle less aggressive. Note also that while a good gunsmith can usually add checkering to the front of a well-built (i.e. not too thin) frame, he can’t often change it. Something to keep in mind.

Let’s also talk magazines. There are many manufacturers, and some are better than others. This is a rather annoying Achilles heel of the modern 1911: there is no longer a standard magazine design. There is no ‘factory standard’. I have had good experiences with Wilson Combat ETM HD magazines and Tripp Powermags. I have also heard good things about Chip McCormick magazines. I would not recommend deviating from these three brands. I would suggest buying one or two of each and seeing if your gun has any preferences, and then buying more of those. Do not cheap out on magazines. Note also that my brand recommendations do not change if you are choosing a 1911 in some not-.45 ACP caliber.

1.) My aforementioned bureau gun.

M&P 2.0 Range Reports

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Alas, I am not (yet) an important member of the Gun Media to warrant getting my hands on weapons that are so new as to be unreleased yet. But I have friends who are. Let’s look at what Top Men think of the M&P 2.0. My overview of the design can be found here.

Our sources really liked the new grip texture. They said it was good enough to not require modification out of the box. Your mileage may vary, since everyone’s tastes are different, but that’s a big improvement. The stock M&P 1.0 pistols have pretty slick grips.

The trigger was always going to be the $64,000 question. And our sources say it’s much improved. Likely totally redesigned. It’s got a very “Apex-like” feel, with much less of a mushy feeling, and a crisper reset. It also felt lighter than an M&P 1.0 trigger. They also got some time on a Performance Center version which had an even nicer trigger and a red dot. This version performed very well.

Accuracy at distance, even with wind, was good. Small sample size, but this is a good sign that S&W has fixed the accuracy issues. We can certainly hope.

I’m hoping S&W gets its act together and makes a good pistol. Competition drives market improvements. Also, note that the M&P series is second only to Glock in terms of aftermarket support, and whoever’s in third place doesn’t come close. M&Ps have a pretty decent lineup of accessories and training aids. So it’s good if they can keep their product solid.

OpenTafl AI roundup: bugs and features

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This post will cover OpenTafl AI changes since the last post I wrote on the topic, further back in the v0.4.x releases. First, bugs!

Let’s do some quick recap. OpenTafl’s AI is a standard, deterministic1 tree-searching AI, using iterative deepening. That means that OpenTafl searches the whole tree2 to depth 1, then to depth 2, then depth 3, and so on, until it no longer has enough time to finish a full search3.

You may have noticed, if you’ve used OpenTafl, that searching to depth n+1 takes a longer than searching to depth n, and that it’s altogether possible that the process above might leave OpenTafl with a lot of time left over. I did not fail to notice this, and I implemented a couple of additional searches (extension searches, as they’re known) to help fill in this time.

The first, I refer to as continuation search. Continuation search takes the existing tree and starts a new search at the root node, using the work already done and searching to depth n+1. Obviously, continuation search doesn’t expect to finish that search, but it will reach some new nodes and provide us some new information. After continuation search, OpenTafl does what I call a horizon search: it finds the leaf nodes corresponding to the current best-known children of the root node, then runs normal searches starting with the leaf nodes, to verify that there aren’t terrible consequences to a certain move lurking just behind the search horizon.

These are fairly easy concepts to understand, my poor explanations notwithstanding. The bugs I referred to in the title are more insidious. They come down to a much more complicated concept: what conditions must the children of a node meet for that node’s evaluation to be valid?

In the iterative deepening phase of the search, the answer doesn’t matter. Remember, OpenTafl discards any tree it doesn’t finish. When we’re doing extension searches, though, we don’t have that luxury. OpenTafl must be able to discern when a certain node has not been fully searched. I added a flag value to the search to note that a certain node has been left intentionally unvalued, which gets set whenever we have to abandon a search because we’ve run out of time. If a node did not exist in the tree prior to the extension search, and it has unvalued children, then it is also unvalued. If a node did exist in the tree prior to its extension search and it has unvalued children, this is okay! We ignore the unvalued children and use the information we’ve gained4. If an unvalued node is left in the tree after those steps, we ignore its value. Any unvalued node is misleading, and we should avoid using its value when deciding how to play.

This issue led to poor play, as both horizon and continuation search had a chance to introduce bad data into the tree. I finally tracked it down and fixed it in v0.4.4.6b.

After that, I came across another few bugs, lesser in severity but still quite bad for OpenTafl’s play: when evaluating a draw position for the attackers, OpenTafl would incorrectly view it as more defender-favorable than it should have been5. OpenTafl also had some trouble with repetitions, incorrectly failing to increment the repetitions table in some search situations. That’s one of the more important gains over v0.4.4.7b—v0.4.5.0b is absolutely incisive in playing out repetitions, as some of the players at playtaflonline.com discovered after the update.

Finally, a few minor time usage bugs are no longer present, although there are some headscratchers where the AI seems to lose half a second or so to some task I cannot locate, and some task it does not count when doing its time use accounting.

That about wraps up bugs. Features, as usual, are more fun.

First, OpenTafl now is willing to play for a draw in rare circumstances. If its evaluation tilts overwhelmingly toward the other side, and it sees a draw in its search tree, it evaluates the draw poorly, but better than a loss.

That depends on the second feature, which is an improved evaluation function. Rather than guess, I decided to be scientific about it: I built four OpenTafl variants, each with a certain evaluation coefficient raised above the rest. Those variants played each other in a battle royale, and based on the outcome, I picked new coefficients. They differ by size; 7×7 boards consider material more heavily, while larger boards prefer to play positionally6.

Positional play comes from the last and most important feature: piece square tables. Credit for the idea goes to Andreas Persson (on Twitter @apgamesdev), who linked me to the chessprogramming wiki article, and also provided a first pass at the tables.

I should back up a bit first, though. Piece square tables are descriptively-named tables which assign a value to having a certain piece type on a certain space. For instance, the space diagonally adjacent to a corner space in a corner-escape game is very important for the besiegers. That space gets a high positive coefficient. On the other hand, the spaces directly adjacent to the corners are quite bad for the attackers, and get a moderately large negative coefficient. OpenTafl’s evaluator handles the exact values.

The benefits of this approach are manifold: not only does OpenTafl know when the opponent is building a good shape, it now has a sense for position in a global sense. (It previously had some sense of position relative to other pieces, but that was not sufficient.) Because of this, it is much better now at picking moves which serve more than one purpose. If it can strengthen its shape by making a capture, it’ll do so. If it can weaken its opponent’s shape, so much the better. The code which generates the piece square tables can be found here7.

The outcome is most pleasing. I can no longer easily beat OpenTafl on 11×11 corner escape boards, and games in that family are presently the most popular in online play. Equal-time matches are all but a lost cause, and I have to engage my brain in a way I never did before if I allow myself more thinking time. Now, I am not all that good a player, and those who are better than me still handle OpenTafl pretty roughly, but it now plays at a low-intermediate level. Given that it barely even existed twelve months ago, I’d say that’s good progress.

  1. Mostly. ↩
  2. Kind of. ↩
  3. More or less. For being mostly deterministic, AI stuff is remarkably fuzzy. On an unrelated note, look! We have new footnotes, with links and everything! ↩
  4. You can construct a game tree where this assumption—that not searching all of the outcomes when exploring an already-valued node is acceptable—causes trouble, but the fault for that lies more with the evaluation function than with the search. In such cases, the evaluation function must be so incorrect as to evaluate a node which leads to a loss just over the horizon as better than a node which does not lead to an imminent loss to a slightly deeper depth. They are quite rare, though, and I haven’t come across one yet in testing. ↩
  5. It was supposed to be a plus sign, but it was a minus sign instead. Oops. ↩
  6. On the to-do list is changing coefficients over the course of a game—brandub is more or less an endgame study, and at some point, the evaluator should prefer material over position in endgames even on larger boards. ↩
  7. I chose to generate the tables because it’s easier to maintain and update. Work for corner-escape 11×11 boards generalizes to most corner escape variants; the same is true for edges. The only boards which really, truly take special cases are 7×7, since the corners are such a vast majority of the board, and moves which might be considered neutral or iffy on larger boards ought to be given a chance—there aren’t many options in the first place. ↩

Design Compromises: A Case Study

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Every design is a compromise. There are no free lunches. And trying to work out the why can be very informative. So let’s take a look at one of my favorite tanks, the M1 Abrams, and look at some design compromises, and their results. Since it’s very nearly equivalent, and designed at about the same time, I will use the Leopard 2 as a point of comparison. The Leopard 2 is somewhat more conventional internally in a few subtle ways.

The most obvious difference is the engines. Both designs have 1,500 hp engines, but where the Leopard 2 uses a pretty conventional twin-turbo V12 diesel, the Abrams uses a gas turbine. This gives the Abrams better acceleration, but also necessitates a greater internal fuel capacity. Where the Leopard 2 can get away with 1,200 L of fuel stowage, the Abrams needs about 1,900 L to meet its (shorter) range requirements. More fuel means more space. We can note that the Abrams has fuel tanks on either side of the driver, in addition to in various other places. The Leopard 2 does not have fuel stored up front in the hull.

The hull front on the Leopard 2 is used to store ammo in a pretty conventional rack. There’s not much in the way of blast venting provision here, so a penetration would be extremely bad news. That said, this is a pretty common place to store reserve ammo1, and hull hits are much less likely than turret hits. Still, from a survivability perspective, this is clearly not ideal.

The Abrams designers were able to shoehorn a few (six 120mm rounds, more of the smaller 105mm rounds) into a compartment aft by the engine, because of the shape of the gas turbine power pack. This rear ammo compartment has blow-out panels and a heavy door to isolate it from the crew compartment, but it’s not a lot of reserve ammo. The Abrams carries the vast majority of its ammo in the turret bustle. On the one hand, this makes subdivision easy. It’s a simple engineering exercise to add blow-out panels to the bustle, and this makes the Abrams among the most survivable tanks in the world.

Storing 34 120mm rounds in the bustle has its disadvantages. It forces a wide turret. Turret height is determined by the desired maximum gun depression, and a wide, tall turret means the armored volume is correspondingly large. The Abrams has considerably more armored volume than the Leopard, both in relative terms (i.e. crew space), and in absolute terms. Because so much of the Abrams’ ammo load is in the turret, there’s a significant amount of armor protecting the side of the turret bustle. More volume means it takes more weight to provide the same level of protection. Or, you have to use more expensive exotic materials (like depleted uranium).

On the other hand, more internal volume is another survivability gain. Armor penetrations are less likely to cause significant casualties or destroy enough systems to score a mission kill simply because there’s more volume to deal with, and volume leads to dispersion, which is the enemy of the shaped charge jet.

To be honest, on these grounds I prefer the survivability over protection. Protection can be added, but it’s much harder to do a redesign in favor of survivability.

We can see another difference in the guns on the latest models. Since the M1A1, the Abrams has been equipped with a license built Rheinmetall 120mm/L44 gun, just like Leopard 2s up to the A5 model. Subsequently, the Germans went to a longer L55 gun for more penetrating power. The Americans have not. So what gives?

Recall that Americans like their depleted uranium. The Germans don’t. Something something environment or something. Anyway, depleted uranium makes awesome armor. It also makes awesome armor piercing rounds. The Americans have done a good job of sinking plenty of R&D funding into new depleted uranium APFSDS rounds. They’re up to a fifth iteration of the design with the M829A4 round. So when adapting a longer barreled gun proved more costly than anticipated in the 90s due to stabilization issues, the US Army quietly dropped the project and stuck with their fancy rounds.

I don’t know if the Leopard 2 didn’t have the same stabilization issues as the Abrams with the longer gun, or if the Germans were just unwilling to change round composition. Regardless, the Germans adapted a longer gun. It means they can use tungsten-based APFSDS rounds, but it also means they will have somewhat more restricted mobility in urban environments.

For this one, six of one, half a dozen of the other. I’m indifferent here, provided both are available. I do wonder if the DU rounds will also perform better in the L55 gun, or if they’re optimized for the L44.

I suppose I should also comment on the engines. I strongly suspect that the Germans made the right choice here with the conventional V12 diesel, though I would strongly prefer an air-cooled model like the AVDS-17902. It’s possible the gas turbine just hasn’t gotten enough development funds, but a diesel engine company can push research into the civilian sector to recoup costs there, in addition to the military. I also approve of forward fuel tanks, and don’t approve of forward ammo stowage. Remember, well-designed fuel tanks provide reasonable supplemental protection.

1.) It’s also used on the Leclerc, K2, and Challenger 2, among others. Doesn’t mean I like it.
2.) Early versions powered the M60 Patton, and the 1,200 hp variant powers the Namer. A 1,500 hp variant is available.

Hudson H9

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For a little bit on Hudson’s no-show at SHOT 2019, and court documents relating to same, go read this article.

It’s being teased, and it’s coming at SHOT, so let’s talk about it. The Hudson H9. Or, what happens when a 1911 and a Glock get drunk one night.

It’s a striker-fired, metal-framed, double-stack pistol. It’s got a sliding trigger, which should feel good. It has an ambi slide release, may have an ambi safety variant (prototypes had one, all the teaser shots don’t), and a conventional rotating takedown lever. And it’s got a weird front end. It appears (and patent drawings seem to back up this) that the really low dustcover and bizarre front end is to put the recoil spring assembly and rotating take-down lever in front of the trigger rather than above it. This would lower the bore axis, which would lower the recoil vector to be more in line with your hand.

And now, a brief aside to step into one of the many minefields of gun discussions, bore axis. Bore axis is how far the center of the barrel is from the web of your hand. It’s also commonly either overblown into “GUNZ WITH A HIGH BORE AXIS ARE TEH UNSHOOTABLE!!1!” or ignored with a “GIT GUD, N00b!!!!” As usual when morons get to keyboards, both parties should be ignored. Clearly, physics tells us there is something to bore axis worth thinking about. It’s why we try to get a grip as high as possible up on the gun. To be closer to the recoil force vector. That works. Every reasonably good pistol shooter knows that works. So all things being equal, a lower bore axis is better. But it’s not a huge deal, because even guns that commonly are called out for a “high bore axis” are still pretty shootable. A higher bore axis will put more emphasis on your recoil control technique in your grip, if you care about fast follow up shots. It’s a thing, but it’s not the be-all, end-all of pistol design.

So a super low bore axis, because we’ve moved some important operating components out of the way, is going to be good for quick follow up shots and gamer-ness. Sweet. Plus, that metal (steel?) frame is going to soak up recoil like a sponge. Again, great for the gamers. And sliding triggers feel really good, and are easier to push straight back to the rear, all other things being equal. Presuming it’s not a stupid-heavy trigger, that should also be great.

Oh, and it’ a proper double-stack, single-feed magazine. You know, like a Glock, or just about any other full-size pistol that isn’t a 1911 these days. It’s a rather fat looking magazine too. List capacity is 15 rounds, at least according to the website. I was hoping for more before going to extenders, maybe 20. Oh well. I’ll live.

From an engineering standpoint, this thing looks like a real winner. So let’s talk outstanding questions:

  1.  Magazines. They’re a new design. Are they reliable? Will they be easy to come by? What will they cost?
  2. Sight Dovetails. Is this a new design, or something established. Hopefully it’s a standard dovetail so we don’t have to wait to see if the pistol is popular before looking for other sight options.
  3. Grip panels. Basically everything I said about dovetails. Are these a new grip panel design? Grips are a bit cheaper to fab, I think, so maybe those designs will come quicker if this is a new thing.
  4. Reliability. Hello 800 lbs. gorilla in the room. Have you done your homework, Hudson? Does this damn thing run and run and run? Or do we have an heir apparent to the Throne of the Feedway Stoppage?

So on the one hand, color me skeptical. On the other hand, I don’t know Hudson’s financial backing or engineering team. So I don’t know what kind of backing we’re looking at. On the one hand, pushing the envelope has gotten us things like Kel-Tec, makers of impossible-to-find vaporware guns, Boberg nonsense that pulls bullets apart, and the ‘recall all the things’ Caracal.

On the other hand, let’s also not forget that Glock was once revolutionary and weird for trying to make a frame out of plastic, and look where it’s got them.

There are a lot of ‘revolutions’ in the gun world that have gone nowhere. And a few that have taken off, and some that just kinda hang around unnoticed. We’ll see what this one brings.

As for my opinion of the H9, well, I am a cynical sort. I’ve already got a lot of really nice pistols. I’ll wait for the initial reviews and reserve judgment. I do like flat-shooting guns, but I generally don’t like being a beta tester. So we’ll see.

See more on range reports from SHOT here!

2016 Tafl Efforts: Results and Roundup

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First off: the inaugural OpenTafl Computer Tafl Open has come to a close. It was a bit of an anticlimax, I must admit, but fun times nevertheless.

To recap, only one entry (J.A.R.L) made it in on time. On January 2nd, I had the AIs run their matches, and it was all over inside of 20 minutes, with a bit of technical difficulty time to boot. You can find the game records here.

To move one layer deeper into the recap, both AIs won one game each out of the match. J.A.R.L won in 22 moves, OpenTafl won in 18, giving the victory to OpenTafl. Disappointingly for me, OpenTafl played quite poorly in its stint as the attackers, allowing J.A.R.L to quickly set up a strong structure funneling its king to the bottom right of the board. Disappointingly for Jono, J.A.R.L seemed to go off the rails when it played the attacking side, leaving open ranks and files and leaving a certain victory for OpenTafl. Deeper analysis is coming, although, not being a great player myself, I can’t offer too much insight. (Especially given that neither AI played especially well.)

I do expect that, when Jono finishes fixing J.A.R.L, it’ll be stronger than OpenTafl is today. He intends on making its source code available in the coming year, as a starting point for further AI development. (If feasible, I hope to steal his distance-to-the-corner evaluation.)

There will be a 2017 OpenTafl Computer Tafl Open, with the same rules and schedule. I’ll be creating a page for it soon.

Next: progress on OpenTafl itself. It’s difficult to overstate how much has happened in the past year. Last January, OpenTafl was a very simple command-line program with none of the persistent-screen features it has today; it had no support for external AIs, no multiplayer, no notation or saved games, and a comparatively rudimentary built-in AI.

The first major change of the year was switching to Lanterna, and that enabled many of the following ones. Lanterna, the terminal graphics framework OpenTafl uses to render to the screen, allows for tons of fancy features the original, not-really-solution did not. Menus, for one. For another, a UI which makes sense for the complicated application OpenTafl was destined to become. Although it’s the easiest thing to overlook in this list of features, it’s the most foundational. Very few of the remaining items could have happened without it.

Next up: external AI support. In the early days, I only planned for OpenTafl to be a fun little toy. At the end of that plan, it might have been something I could use to play my weekly (… well, kind of) tafl game without having to deal with a web interface. (For what it’s worth, Tuireann’s playtaflonline.com renders that goal obsolete, unless you really like OpenTafl.)

Later on, as I got into work on OpenTafl’s built-in AI, I realized what an amazing object of mathematical interest it is, and that it has not, to date, seen anything like the kind of study it richly deserves. As such, I decided I wanted OpenTafl to be a host for that sort of study. Much of what we know about chess, go, and other historical abstract strategy games comes from the enormous corpus of games played. That corpus does not yet exist for tafl games, the amazing efforts of people like Aage Nielsen and Tuireann notwithstanding. The quickest way to develop a good corpus is to play lots of games between good AIs. Good AIs are hard to come by if every AI author also needs to build a UI and a host.

So, OpenTafl fills the void: by implementing OpenTafl’s straightforward engine protocol, AI authors suddenly gain access to a broad spectrum of opponents. To start with, they can play their AI against all other AIs implementing the protocol, any interested human with a copy of OpenTafl, and possibly even the tafl mavens at playtaflonline.com. Not only that, but the AI selfplay mode allows AI authors to verify progress, a critical part of the development process.

Multiplayer was an obvious extension, although it hasn’t seen a great deal of use. (There are, admittedly, better systems out there.) It proved to be relatively straightforward, and although there are some features I’d like to work out eventually (such as tournaments, a more permanent database, and a system for client-side latency tracking to allow for client-side correction of the received server clock stats), I’m happy with it as it stands.

OpenTafl is also the first tafl tool to define a full specification for tafl notation, and the first to fully implement its specification. The Java files which parse OpenTafl notation to OpenTafl objects, and which turn OpenTafl objects into OpenTafl notation, are in the public domain, free for anyone to modify for their own AI projects, another major benefit.

In defining OpenTafl notation, I wanted to do two things: first, to craft a notation which is easily human-readable, in the tradition of chess notation; and second, to remain interoperable with previous tafl notation efforts, such as Damian Walker’s. The latter goal was trivial; OpenTafl notation is a superset of other tafl notations. The former goal was a little more difficult, and the rules notation is notably rather hard to sight-read unless you’re very familiar with it, but on balance, I think the notations people care about most—moves and games—are quite clear.

Having defined a notation and written code to parse and generate it, I was a hop, skip, and jump away from saved games. Shortly after, I moved on to replays and commentaries. Once again a first: OpenTafl is the first tool which can be used to view and edit annotations on game replays. Puzzles were another obvious addition. In 2017, I hope to release puzzles on a more or less regular basis.

Last and the opposite of least, the AI. Until the tournament revealed that J.A.R.L is on par with or better than OpenTafl, OpenTafl was the strongest tafl-playing program in existence. I’ve written lengthy posts on the AI in the past, and hope to come up with another one soon, talking about changes in v0.4.5.0b, which greatly improved OpenTafl’s play on large boards.

Finally, plans. 2017 will likely be a maintenance year for OpenTafl, since other personal projects demand my time. I may tackle some of the multiplayer features, and I’ll probably dabble in AI improvements, but 2017 will not resemble 2016 in pace of work. I hope to run a 2017 tafl tournament, especially since the engine protocol is now stable, along with OpenTafl itself. I may also explore creating a PPA for OpenTafl.

Anyway, there you have it: 2016 in review. Look for the AI post in the coming weeks.