Going for super-reliable AR upper

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DirtyBrad

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I've been messing around with a new upper for my AR. My goal is a short, but non-NFA, barrel and maximum reliability. This will be my go-to gun and one I'll be taking to classes, so what I care most about is that it runs all the time.

I'll be putting an optic on this eventually, but I'm going to stick with just irons for now.

I'll be putting it together in the next couple of weeks. Nothing is set in stone, but based on the parts I have, I think I'm about ready. Thought I'd get your thoughts.

14.7" Armalite barrel, 1:9, chrome-lined, mid-length gas system, M4 extensions
Pinned/welded A2 FH
Low-pro gas block
Colt M4 upper
Colt FA BCG w/black insert and CS spring
H buffer
DD 10" Lite rail
MI folding front and rear sights

Looking forward to hearing your thoughts.

Thanks
 
I think you've got a pretty darned good plan there! Someone will come along and mention a G.P. upper, but then again, that's not really an "AR 15" per se, now is it? That'd be some other rifle TYPE.
 
The folding FS is not necessary, and is one for thing to go wrong as compared to a fixed FS, but it's personal preference. I think that setup will work just fine. I would also go for a 1:7 twist, as it shoots the heavier bullets currently en vogue better than a 1:9. The 1:9 will work, though.

One of the best things you can do for long-term durability is "upgrade" the bolt and carrier to military spec, which you have done.

Once you get it built, take a carbine course. You will learn more about how to run the rifle there then you will anyplace else, and you'll also find out how well your gear works.

Mike
 
Super-reliable?

I don't know...

Is there a way to put a Mini-14 receiver on an AR lower?:D
 
I've got a really reliable and a really accurate .223 semiauto in my safe, so I can make a recommendation, then.

One's a Mini and the other's an AR...:D
 
Thanks for the responses.

As far as 1:7 goes, all things being equal, I'd prefer it. Currently, I can either go with 1:7 Colt carbine gas system or 1:9 Armalite mid-length. I realize the differences in either set-up are very small, but I'm currently picking the middy over the 1:7.
 
If you got to have a 16" barrel anyway, it might as well be a barrel, and not a long flash hider to make it 16" legal.

No point in giving up any more velocity / performance then you have too.

Velocity is what makes the .223 work.

rc
 
I dunno about a midlength 14.7". The main "issue" that a midlength 16" corrects, compared to a carbine 16", is the "violent" gas system. Which is typically only an issue in carbines which have the blue extractor insert, 4-coil spring, and a "standard" buffer. Mil-spec extractor and H buffer, and you should be good to go with a 14.5" (or 14.7") barrel with a CAR gas system. If anything, with the correct parts, a more "violent" system should help with extraction.

Use Pmags, and you should be good to go.

My theory on AR vs. AK reliability, anyway, is that 99% of it comes down to the mags, and Pmags have finally put the two weapons on even footing.

Look at an AK mag next to a GI aluminum AR mag, and there's no comparison whatsoever. You could use an AK mag's feed lips to mash up a couple dozen AR mags, and it'd still feed perfectly. AR mags are very easy to make inoperative or unreliable by just dropping or kicking them a couple times.

Also, AK mags have a continuous curve inside, allowing the use of a true anti-tilt follower. AR mags are straight, then have a bend, then are straight again, which means that the so-called "anti-tilt" followers only tilt a little less than the old ones. They still wobble all over the place compared to AK followers.

But then Pmags are made of good quality polymer which can't bend permanently like soft aluminum does, and they come with feed lip protectors, and they have a continuous internal curve and a true anti-tilt follower.

The only difference left is the rock-and-lock mag system on the AK, vs. straight-in for the AR. Much as a lot of people hate rock-and-lock, it gives you a phenomenal amount of leverage. You can seat a fully loaded AK mag using just your pinkie finger. Not a chance of pulling that off with an AR. Though Pmags do help. They are much easier to seat than GI mags, anyway.

I think most of the soldiers over in the sandbox aren't going nuts over Pmags for nothing.
 
At carbine classes, the vast majority of the malfunctioning AR-15's have been home-built or messed with significantly by the user. While it is obviously possible to build an accurate and reliable AR-15 upper, the chances are much worse for an amateur gun-wrencher compared to a professional builder (and that is not to say that everyone who calls themselves a "pro" is qualified either).

In summary, I'd say that unless you have a track record of building extremely reliable uppers and diagnosing and fixing problems, money spent on an "ultimate" set of parts that you're going to put together would be better spent buying a complete rifle or upper from a source known for reliability and accuracy.

Ultimately, the point is to learn how to use the AR-15 effectively. To do that you need a properly-running rifle.
 
Zak, thank you for the response.

I'm generally mechanically inclined. Former bike mechanic, work on my cars, hobby metal working, that kind of thing. I've built a few uppers now, but I'm no kind of expert.

I'm curious, what types of upper failures do you see from home builders?

For this one, I'll be having the gas block (a low-pro) pinned on when I have the FH attached. So, all I'll really be doing is attaching the barrel, rail, and sights. I'll be using the torque wrench on everything. I've got moly lube for the barrel nut and Loctite for the small screws/bolts.

That seems about as straightforward as it gets and the parts are all new and of good quality, so I feel pretty confident that I can do as good a job as the factory.

But I'm the first to admit I could be reading things wrong. I'm happy to learn from those with more experience.
 
I've built and/or modified a bunch of uppers, and even bucked the trend by using match triggers, modified uppers, and 1911's (actually "2011") at high round count training classes. However, my most-used uppers are factory- big factory (RRA, etc) or small builder (like MSTN or Noveske).

Most of the time, builds go together fine and things work and the upper shoots well. Sometimes it doesn't, for whatever reason: could be interaction between parts, one part not quite right/square/true, or a poor choice of parts. When this happens, you have a lot of money tied up in parts, with a potentially hard to diagnose problem. It can be hard to convince a manufacturer there's a problem with his part when you have a home-built upper with a bunch of other parts and it's not definitively his problem.

Those are some reasons why I prefer to just buy a top-quality upper built by someone who puts together hundreds of absolutely reliable sub-MOA uppers a year, has a library of knowledge of what parts work best together, and a lot of reliability data of the various configurations put together (along with technique during assembly to ensure accuracy). If it doesn't run or isn't up to accuracy spec, it's "their" problem.

Anyway, that's my perspective on it. Putting together your own specced out rifle can be fun, but IMO a questionable use of time/money if your goal is to get to training. Nothing wrong with enjoying the gunsmithing side of it, though.
 
Zak,

I hear you. I probably should have added to my original topic that I'd like to be doing this myself. I do enjoy working on things and find it the best way to really learn.

Rifle class is still several months off. I'll be putting plenty of rounds through this before then. Hopefully, that will shake out any gross errors I've made.

My plan for class is to bring two rifles. I don't want to waste anyone's time diagnosing. Your advice definitely makes sense. I'll look to bring a factory gun as the back-up.

Two more questions for you:

1. Have you seen any issues in carbine classes with free-float rails? I've used a couple and they do seem very solid, but I wonder if that environment shakes any loose or exposes any other issues.

2. How does the 14.5" barrel do with the mid-length system? I opted for that due to the claimed (albeit small) increase in reliability and perceived recoil, but now I'm seeing a couple thoughts that short-stroking could be a problem. I'm encouraged by the fact that plenty of reputable builders, like Noveske, are offering them.

Again, thank you for the responses.
 
1. No problems with FF rails. Swapping handguards/FF tubes on a factory upper is unlikely to have reliability effects unless the installation is seriously screwed up.

2. It should be fine for reliability. I had a 14.5" w/ MLGS and it ran fine. However, I would counsel against an extra heavy BCG and/or buffer. Start with stock-weight parts and only increase mass if you need to to fix a specific problem. Increasing reciprocating mass and thereby increasing cycle time will often mask other problems, notably magazine problems.

Here's the 14.5/MLGS I had at one time:
A100_1708_img.jpg
............... Larger version of above photo.
 
If money is no object the H&K 416 cant be beat in the reliability department
Click to expand...
I would put my POF head to head with a H&K 416 any day. Funny as it sounds, i was just at the knob creek mg shoot, and the ONLY gun i saw malfunction was a H&K....:D:D

DirtyBrad--why are you stuck with a 14.whatever barrel, and a flash hider, why not get the extra fps with the 16", and the ability to sway muzzle devices whenever you want? Kinda stupid IMO.
 
Pinned and welded.

Good point about the weight. I've got an FA BCG. I'll start with the standard buffer.
 
You're pretty close to what I built for myself: CMMG 1/7 chromed lightweight middy with fixed FSB (one less thing to go wrong) and a flat-top upper. I have the Larue rear sight (one less thing to go wrong) and Aimpoint M4s on mine, but the optics is a personal preference.

I've been using the bravocompany extractor upgrade (Wolff spring with black insert and o-ring) and have had no FTEx problems of any kind. OTOH, the 20" AR has the same kit installed too.

I get about 2MOA with 55gr and the 1/7 barrel, 75gr gets me 1.2-1.5MOA. CMMG does good work, but I did have to wait. The 20" barrel is also by them and has similar accuracy.

I've used this rifle at our local practical rifle matches with no problems. I also had no failures at the 4 day class I did.

I agree that Pmags offer a significant increase in reliability over any metal mag I've seen. Mag failures used to account for most of the problems people around me have had with ARs. I don't recall seeing any mag related failures where the shooter was using Pmags.

BSW
 
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