Advice for a nerd's first sporting rifle build


#1

I’ve been looking to build my first (CA compliant) modern sporting rifle, and have been reading through lots of articles such as the AR15 Primer on Calguns and consulting with a knowledgeable friend to get familiar with the basics. My goals are:

  1. Learn the details behind the AR-15 platform design
  2. Pick components that match my ergonomics
  3. Own a semi-auto rifle with high reliability and flexibility to modify (so I can easily do A/B testing)

Here’s what I’m leaning toward including, and would appreciate feedback if there are compromises with these choices I might not realize:

  • 16 inch barrel: Prefer shorter carbine style
  • Gas impingement design: It’s supposed to be an AR-15 after all
  • 223 Wylde barrel: 223 Wylde is supposedly more accurate, and I plan to mostly shoot reloaded 223. Expect to mainly shoot 50-100 yards, so could be talked into a 5.56 barrel if I’m not realistically going to be seeing any accuracy benefits.
  • Fixed mag: I may be teaching others with this rifle, so an adjustable stock is important to accommodate other sized shooters. The CompMag seems to be a reasonable solution, and the Juggernaut Hellfighter seems like an interesting alternative. I expect to eventually get a Thordsten stock to evaluate if the loss of ergonomics is worth the detachable magazine feature.
  • Complete Upper: I’m not quite feeling bold enough to build out the upper, so leaning towards a complete upper from Aero Precision that includes everything except the BCG and charging handle. Most complete uppers have a flash hider on the barrel. Is it safe to assume these are threaded and can be removed or replaced if I later decide to go to a featureless, detachable magazine design?
  • KeyMod upper: It seems there is better availability of KeyMod accessories vs MLok.
  • Stripped Lower: The choice of trigger is important, and I might want to have ambidextrous controls, so plan to build out the lower receiver from a stripped lower.

I would also welcome any recommendations on specific brands or components as well. Many thanks!


#2

16 inch barrel: Prefer shorter carbine style

Perfect barrel length. I’d suggest getting a barrel with a mid-length gas system, not carbine-length gas. Guns with a carbine-length gas system in a 16" barrel are generally quite overgassed. Mid-length gas is a good best-of-both-worlds.

Gas impingement design: It’s supposed to be an AR-15 after all

Agreed. The gun is designed as a DI gun. There are plenty of good non-AR piston guns out there too. But an AR in piston form is IMO a solution in search of a problem. Render unto Stoner the things that are Stoner’s.

223 Wylde barrel

Probably doesn’t matter if you’re not doing long-range comeptition, but no reason not to go Wylde.

Fixed mag

The Hellfighter seems pretty ingenious.

Complete Upper: I’m not quite feeling bold enough to build out the upper, so leaning towards a complete upper from Aero Precision that includes everything except the BCG and charging handle. Most complete uppers have a flash hider on the barrel. Is it safe to assume these are threaded and can be removed or replaced if I later decide to go to a featureless, detachable magazine design?

Aero’s good to go. If the barrel is ≥16" and it doesn’t say that the flash hider is permanently attached, it’s safe to assume you can remove the flash hider with just a wrench. If you’re going to be doing any work on the gun beyond that, I highly recommend getting the Magpul BEV block. Makes it super easy to hold the gun in a vise.

Charging handle doesn’t matter much. Get a Geissele ACH if you want maximum cool guy points, but honestly my $30 Strike Industries one works great. I would recommend getting something with a bigger latch than the milspec handle though. As for BCG, I highly recommend a Toolcraft nickel boron one. Toolcraft is a good company, the nickel boron gives you a really smooth action and is much easier to clean than normal finishes, and you can find them for ~$95.

KeyMod upper: It seems there is better availability of KeyMod accessories vs MLok.

The military is standardizing on MLok now, so over time things are going to be going more and more in that direction. Doesn’t matter much, but given the choice I’d go with MLok.

Stripped Lower: The choice of trigger is important, and I might want to have ambidextrous controls, so plan to build out the lower receiver from a stripped lower.

Cool! I’d suggest a Geissele G2S. They run 20% off sales a couple times a year. Short of that the ALG ACT is pretty good too. Only other stuff here is that you might want an aftermarket grip, an enlarged trigger guard, and a QD end plate.


#3

As a decent, affordable alerternative to Giessele, I’ve enjoyed my drop-in Velocity triggers, with pre-set weights of 3.5/4.5lbs and straight/curved options.

Fair warning about the hellfighter and all the other fixed mag solutions that involve breaking the action open to change magazines: they substantially complicate the process of remediating malfunctions, specifically a double feed, where you will need to drop your magazine when the bolt is halfway in the upper receiver and halfway in the buffer tube (thus preventing the upper from being lifted up).

The hellfighter completely prevents you from locking the bolt back, and I’ve also read that there are issues with the bolt getting caught on the magazine follower as it moves forward. Folks have remedied this by modifying their magazines, but that’s not something I’m interested in doing. From this perspective, the external magazine loader solutions, where the magazine stays inside at all times, seem to do a better job of keeping the rifle functioning as intended.

If you’re mostly bench shooting, featureless and Thordsen is probably a better option for you. The Thordsen ergonomics are quite good actually, though the stock is heavy. I agree that giving up stock adjustment is tough.


#4

The Geissle triggers are great, and I have them on two of my ARs.

I’ve recently gotten to use some Timney triggers, which are also very good. My Geissles are two-stage (my preference) and the one Timeny I’ve installed is single-stage, so I can’t really yet give an apples-to-apples comparison, but I will say this for the Timney – it’s a complete drop-in package that’s dramatically easier to install than anything else out there.

I have a two-stage Timney AR-10 trigger that’s just waiting for a gun (hopefully the new LMT in 6.5CM), so I’ll be able to put it against my LMT LM8MWS in .308 with a Geissle two-stage (I don’t recall off the top of my head which one) and do a more direct comparison.


#5

I will give a thumbs up for Timney triggers; I have one in my Armalite AR-15 (model M153GN18) and I’m quite happy with it. Armalite doesn’t spec exactly which Timney trigger they are using, but I suspect it is the AR-15 Competition trigger ($240 which isn’t cheap). It is single-stage but Timney has two-stage AR-15 triggers now as well if that is your thing.

For a less expensive trigger, I can also give a thumbs up to the ALG ACT. I replaced the stock trigger in my Stag 3T-M with this trigger and it is VASTLY better than the stock mil-spec trigger (but not up to the standards of the Timney). For $70 it is a bargain.


#6

Awesome tips and recommendations- many thanks all!

Regarding fixed mags, the CompMag seems to be a design that should allow for fixing misfeeds relatively easily without breaking open the action. Anyone have experience with these?

Regarding triggers, I’m going to test drive a Giessele 2 stage trigger in a friend’s setup to see what I think. A 2 stage seems very suitable for bench shooting, and I could see myself liking it generally.

I’m beginning to re-consider the idea of building out the upper vs. buying a complete one. How hard or easy is it to assemble from parts? I believe building one out would include assembling the upper receiver (with port door and forward assist), handguard, barrel, gas block and gas tube. I consider myself relatively handy and have the tools, but if there is much opportunity to mess something up as a first time build, I’ll play it safe and go with a complete upper. The main reason I ask is because availability of the complete upper I want is pretty slim, plus I wouldn’t mind getting a fluted barrel for extra bling. :sunglasses:


#7

I recently finished a build that involved an pre-assembled upper receiver (installing the dust cover didn’t seem like a good use of my time), but I purchased and installed separately the barrel, handguard, gas block, and gas tube. I am not an experienced machinist or a builder of anything by profession but am confident following Youtube tutorial videos. I think you can definitely handle it.

The AR15 gas system is really simple. It’s just a matter of torquing things to spec and lining up all the corresponding holes.

Frankly, installing the lower parts kit is more difficult/annoying than the main parts of the upper. The handguard I bought (Midwest Industries G3 lightweight) came with a barrel nut and a wrench for installation.

My rifle shoots relatively straight and does not malfunction upon initial testing, so I know I didn’t screw up anything big time :).


#8

Assembling an upper from parts is pretty easy, and makes for a really fun project. If it’s your first one I’d set aside a few hours. You’ll need a little bit of gear:

  • Bench vise
  • Magpul BEV block
  • Armorer’s wrench (you won’t need this if the rail you buy comes with its own wrench tool)
  • Torque wrench with a 1/2" drive that goes up to about 80 ft-lbs. Most of the time you’ll need to torque the barrel nut to the 30-50 ft-lbs range.
  • Punch set and an armorer’s hammer. I’d suggest also getting a roll pin punch set
  • Plain old adjustable wrench and a screwdriver with some hex bits
  • Rocksett for your gas block and muzzle device. I strongly favor clamp-on gas blocks instead of set-screw ones, but that’s not a universal opinion.
  • Blue loctite for any small set screws on the handguard
  • Antiseize compound for the barrel nut threads

Have fun!