Parvusimperator’s Light Rifle

As per usual, I wanted to do another AR-15 build, which of course, needed a concept. I decided to try for a Light-ish rifle. I’m gonna pick some parts on the lighter side of things and see how I like the result. There are some exceptions, which I’ll get into below. Also, if possible, I wanted to give one of those long handguard things a try, see why everybody likes them. And I’m going to make this a nice, generally high-end race-ish build. So let’s cue the music.

Receivers: Mega Arms NiB-coated billet set
Well, that ended quick. Just kidding. Really though, I bought these because they look freaking cool. NiB (Nickel Boron) finish is pretty, and Mega Arms makes nice receivers. Billet receivers are heavier than forged, in general. Oh darn. Let’s look at the receivers themselves in detail:

Upper Receiver:
Well, it’s NiB coated, which looks cool. Internally, this should be pretty slick. Otherwise, it’s mostly adding a bit of bling that we can pretend is something vaguely resembling practical. This is a pretty typical billet upper, with some details particular to the manufacturer to make it look cool, and provision for a forward assist and dust cover.

Lower Receiver:
It’s also NiB coated. Plus, matched billet set, so the design is supposed to flow nicely. Blending and all that. Woo. There are a couple other things of note here that are nonstandard. First, there’s a small setscrew at the back to control fit of the upper and the lower and remove any wobble. Not that the wobble matters, but it’s nice to be able to take it out, get that custom gun feel. We also have an extra bit on the right side–a southpaw bolt release! There’s a button on the right and a longer guide rod so that a southpaw shooter can release the bolt easily with his support hand when he reloads. Cool. Note that there’s no way for him to lock the bolt back with this particular gubbin, but that’s okay. Bolt lockback is nearly always an administrative thing; it doesn’t matter if it’s awkward. Also, the bolt catch is to be held in place with an included setscrew, not a roll pin. Great! Roll pins are of the devil anyway, especially that one, which is about the most awkward thing to install.

Barrel: Daniel Defense 16″ Lightweight Profile CL
That’s more like it. It even says lightweight in the name. Anyway, I went with Daniel Defense because they have a good history of making quality AR barrels, 16″ because I don’t want to bother with pinning the muzzle device or NFA paperwork, and chrome lining (“CL”) because duh, chrome line that barrel for best barrel life results. The lightweight profile is what was originally called for by Stoner in the basic AR-15/M-16A1 design, so we’re in good stead here. Plus, I’m not a benchrest shooter, so I don’t want a barrel that weighs as much as a Camaro. Light rifle, lightweight barrel profile. Perfect for the Run ‘n’ gun.

Handguard: BCM KMR 13″
Oughta make up for all those places I opted not to cut weight. Note that this is not the KMR-Alpha. This is Original KMR, made with BCM’s fancy, proprietary, and apparently hard-to-find aluminum-magnesium alloy. Just like a fancy racing engine block. And it’s laughably light. Holding the handguard in your hand is like holding nothing at all. It’s stupid light. There’s basically nothing to it given that it’s over a foot long. Why 13″? Because I wanted to have a long handguard to see what all the fuss was about. But I still wanted a bit of barrel at the end for the narrow firing port drills you sometimes see at matches. This fits the bill for both. Plus, it’s got the modular keymod interface. Is keymod better than Mlok? I have no idea. I just like this handguard design. I figure both will be around for a long time, because people hang on to guns for a while.

Muzzle Device: Precision Armaments M4-72
I could probably have gotten a lighter muzzle device. I don’t care.1 The M4-72 is universally acclaimed as a super effective muzzle device, coming in at or near the top in several effectiveness tests. It is also apparently horrifically loud. I do not care about this either. Ridiculous race gun comps are always something I’ve been interested in trying. So here it is. One of the baddest of the bad, if you can take the abuse. Or, I guess if people around you can take the abuse.

Gas Block: BCM low profile .625″
Not much to say here. It’s a gas block. It attaches via setscrew, mostly because I lack a drill press to pin it properly. Oh well. .625″ because that’s the diameter of my barrel at the gas port. It is not adjustable, because I don’t really want to fiddle with gas systems too much. I don’t tweak rifles to shoot as light as possible for some custom load. I like my rifle to run with any reasonable factory load.

Gas tube: BCM midlength
Yes, I bought a gas tube. No, there’s nothing special about it. Makes rifle do that autoloader thing.

Bolt Carrier Group: WMD Guns NiB-X coated M16 BCG
Here’s another place where I could have saved some weight, but didn’t. Personally, I’m not a huge fan of low-mass components in the operating system, because I like unfussy, reliable rifles. This is one of the few places where there is mass in an AR-15, so of course someone is gonna try to cut weight here. If you go with a reduced-mass BCG, you nearly always need to tune your gas system for correct functioning. Since I’m not the biggest fan of fiddle-farting around with the gas system, and I have no capacity to do so on this rifle as designed, I kept the stock-dimensioned BCG for reliability. I don’t like fussy, high maintenance guns. NiB coated because my upper is NiB coated, and NiB on NiB is going to give me maximum lubricity. Plus, it looks really cool.

Buffer system: BCM milspec buffer tube, castle nut, receiver end plate, carbine buffer, carbine buffer spring
Not much interesting here. I need a buffer system to make the rifle one correctly. So I got one. It’s all pretty standard stuff. Milspec buffer tube, though it doesn’t really matter as long as it’s consistent with your stock. Castle nut and receiver end plate are also needed, and stock parts, and boring. Nothing fancy here. The buffer is carbine weight, mostly because that’s what came in the kit. I may tinker with that a bit, but Obsessive Buffer Tweaking Syndrome has screwed up many perfectly good guns. So…maybe not.

Stock BCM Gunfighter FDE
This stock is a good balance between weight, comfort, and durability. It’s one of the lighter stocks on the market, among the strongest in abuse/drop tests, and is pretty comfortable as far as cheek weld goes. There’s a rubber pad on it too, not that a 5.56 AR is abusive at all. There are lighter stocks, but most of them are less comfortable. Or I could have just gotten a backplate for the buffer, but that wouldn’t be adjustable. And I refuse to be that silly. Plus I like having features that were on the ban list for the ’94 “assault weapons” ban. Makes me feel warm and fuzzy. Oh, and I picked Flat Dark Earth (FDE to the cool kids, tan to everyone else) because it looks cool, and I’ve got a sort of two-tone look going on.

Various Upper and Lower Parts:
I’m going to list these out, grouped by function, because a bunch are decidedly not standard parts. I rolled my own lower parts kit for this one.

Forward assist: BCM forward assist and spring
Well, the upper receiver has a slot for one, so I got one. It’s a stock part. Moving on.

Dust Cover: Strike Industries Enhanced Ultimate Dust Cover
I got this because installing a dust cover is really annoying. This one is much less so.

Charging handle: Mega Arms Grip Charging Handle
This one came with my upper. It’s got some more grippiness, and it’s a billet part, but otherwise it’s a stock design. I’m fine with that for now. I haven’t had one of my guns jam up real bad, so I haven’t had to really abuse a charging handle. Maybe in the future I’ll get a fancy one.

Mag Release: Colt mag release spring, colt mag button, Norgon ambi mag catch
I got the Norgon ambi mag catch because I figured it’d be pretty silly to have an ambi bolt release but no ambi mag release. I got the Norgon one because it’s well made, puts the mag release in the same place for southpaws and even has an NSN. Other small parts are Colt because I like Colt stuff. They make good small parts.

Bolt release: Colt spring, Seekins Bolt Release Catch
These are added to the already-supplied extended guide rod to enable the southpaw-friendly release functionality. Colt spring because I still like Colt. Seekins catch because it’s a little bigger, and I like the look. Plus bigger is easier to smack when you’re in a hurry.

Safety: Battle Arms Development Ambi Safety
Again, ambi makes more sense as an all-or-nothing thing. Plus, I like ambi safeties in general, and I’m not sacrificing anything. Battle arms makes a really nice one that lets you choose from several different shapes of lever that they make. They come with a safety detent and safety detent spring.

Grip: TangoDown BG-17 FDE
FDE because two-tone. TangoDown BG-17 because it’s a really comfortable grip. It’s my favorite from testing several. And no, I don’t like the ‘more verticaler’ grips they have now. TangoDown’s grip is also shaped to keep your hand high, and a high grip is a better grip. Also, TangoDown actually makes grips in sizes for people who have big, manly hands. The BG-17 is the larger size, the BG-16 is the smaller size. Same great comfortable shape. Since I have relatively large hands, I went BG-17. Interestingly, all the goofy vertical grips seem to be made tiny. No idea why, but it’s another reason for me to not like them

Buffer retainer: Colt buffer retainer detent, Colt buffer retainer spring
Really, there’s nothing to see here. These parts are required so your gun works right. There’s nothing special about them. I like Colt, so I got ones made by Colt.

Receiver Pins: Battle Arms Development Enhanced Pin Set
These hold your receivers together. You need some pins, and the corresponding pin retaining detents and pin retaining springs. I like the Battle Arms set because they shape the pins a bit more to make them easier to push and pull with your fingers. It’s the little things. They also include a little magnet to hold the detents while you install the pins. It’s the little things.

Trigger: Geissele SSA-E
If you thought I was going to put a stock trigger in this gun, you should go play in traffic. I like Bill Geissele’s triggers, and his SSA is pretty much my go-to trigger. I went with the SSA-E for a little bit of match-ness. I might go with a more competition trigger once I get a feel for this one and run it. That trigger might be the Geissele SD-E trigger, or maybe the Hiperfire 24C that I’ve heard so much about. I’ll keep you posted.

There she is, though she still needs a name and an optic. And then it’s off to the range! Watch this space for more details.

Oh, and in case your curious, she weighs 5.975 lbs unloaded, with no optic. A hair under six pounds is pretty good, I thought. Especially because I didn’t get too obsessive.

1.) Technically, I could also have gone with no muzzle device. But that’s just silly. If you seriously considered this, then you’re dumb. Or too weight obsessed. Possibly both.

7 thoughts on “Parvusimperator’s Light Rifle

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  3. Arathar

    Maybe check out the Brigand Arms woven carbon fiber handquard, holds over 100 pounds but its the lightest on the marked!

    Reply
    1. Fishbreath

      Just wanted to say 1) hello and welcome, and 2) you’re now approved for comments sitewide, so you shouldn’t have to wait for my slothful moderation anymore. Parvusimperator will undoubtedly be along in the not-too-distant future to comment more topically on your comments.

    2. parvusimperator Post author

      Oh those are cool. I’ve gotta check one out in person. Sigh. Of course, it would show off my boring phosphate-finished, unfluted barrel that way. Sigh.

      Thanks for the tip. Also, welcome!

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