Cheap AR builds, high round count.

[Dr.Rob]

This keeps coming up at various forums.

If you built a cheap AR what was your round count before parts breakage? And what broke? Did you get it up and running quickly?

Please only reply if you have FIRST HAND knowledge and ran the guns reasonably hard.

This keeps coming up in discussions like 'brand X rifles never even make it though a class' or 'my PSA build is just as good as your Daniel Defense!'

 

[Robert]

Rob, you know my AR and you know it was built from left over parts donated from various sources. It's a mixed bag of Rock River, Colt and GI parts. I have thousands and thousands of rounds through it with no major breakages. I keep squirting oil on the bcg and she keeps humming right along.

 

[FL-NC]

My clunker AR didn't start breaking things until I was maybe 20k rounds into it. At this point I am on barrel #4. I don't replace barrels until they stop grouping at all, and most shooting happens at 100 meters and closer with this gun. I have severely grooved a GI buffer, at different times broken every fire control group part, several extractors and sets of gas rings, and 1 or 2 hammer pins. One time the J pin fell out of the hammer and it went full auto for about 6 rounds. I think the strangest was when the front pivot pin broke into 2 pieces when separating the upper from the lower. I want to stress that this gun has been through ALOT. It has served solely as a range and training gun for 20 years, with large quantities of GI ammo being used. None of these problems were difficult for me to fix as I have been building AR's since the 80's. With the exception of the barrels, the repairs weren't expensive either. I use DPMS barrels. I feel I get my money's worth out of them.

 

[Charlie98]

My buddy bought a no-name assembled upper, it has about 5000 rounds through it. Last year the bolt sheared about 3 or 4 lugs off. Looking at the bolt, I'm guessing they all didn't shear off at the same time... but as the load increased on the remaining lugs, they started to fail one by one. Some people don't understand that in the AR, things like the bolt are a wear item... they will fail, eventually, over time.

My RRA assembled upper has about 7-8K through it, much of it in heavy sessions (1K in 2-3 days with no maintenance except a squirt of CLP on the bolt in the morning) and it's still running strong..

There is an incredible thread on this subject over at ARF, I took the time and read through pretty much all of it. It was started by the guy that runs one of the machine gun rental ranges in Las Vegas... he pretty much lays it out all the way.

 

[SamT1]

From my experience as a range rat and AR enthusiast. Problems with inexpensive AR’s and piece together jobs usually present them self right out of the box. I’d say if it will run 3 mags through it in a 30 minute period it’s probably good to go.
I have too many to have any of my own with high round counts though (5k plusrounds) . The main differences I see with cheap and expensive is how well the fit is between receivers, goes for buttstocks too I hate a rattle stock. Usually more $ is more accurate. Usually more $ is lighter weight on stuff like foregrip and stock.

It really seems to me like the design has been standardized well and machine tools have made leaps since the 90’s and now even the cheapos are reliable barring some error QC missed that presents itself immediately or quickly. I believe when you pay more you buy fit and finish, accuracy, weight.

 

[IndianaBoy]

In my experience, inexpensive ARs that have problems are usually built incorrectly.


Misaligned gas blocks. Springs installed in the lower improperly. Kitchen table trigger jobs. Improperly torqued barrel nuts.


A friend of mine bought some no name cheap lower parts kits from some no-name distributor on ebay. The springs were JUNK and his rifle was a single shot. I gave him a spare mil-spec FCG that I had laying around and cured his issues.


My 'cheap' build where the barrel is a PSA Freedom 1-7 4150 CMV Nitrided barrel, and the bolt carrier group is one of their premium BCG sourced from Toolcraft.

About 2k rounds through it so far, which I don't consider to be high round count.




My 3-gun rifle has about 10k rounds through it. Original bolt and barrel still. DPMS 416 Stainless MK12 barrel, CMT/Stag HPT/MPI tested bolt.




I call them cheap because I pick and choose parts based on my perception of value. I'm not interested in a rollmark, but in how a rifle performs.



I haven't broken a bolt yet. It won't surprise me if I shear a lug in the 3-gun rifle. I scoped the bore and there is a LOT of flame cracking and erosion. I don't know how much accurate life is left in it. I will retire the bolt when I retire the barrel. Maybe another season? It is heavy but it shoots very nicely.

 

[IndianaBoy]

Oh I did just think of one.

I broke a firing pin retaining pin in an AR pistol, pretty low round count.

11.5 PSA Nitride barrel.
PSA bolt carrier group.

I suspect that the firing pin retaining pin was defective with a crack or something, that was invisible to the naked eye. It broke at less than 500 rounds. When it broke, the gun was locked up and completely inoperable. Required disassembly to rectify.


AR pistol was being shot suppressed, and I think that may have contributed. AR pistol barrels are ported to operate without a silencer. With a silencer in place, they are usually WAY overgassed. After this parts breakage, I added an adjustable gas block AND an H3 buffer. That AR pistol is much smoother now.


Just goes to show you, the smallest of parts failing can take your weapon down.



This build is pretty ghetto.... yes, I was using hose clamps to affix both a light and a sling mount. It works fine.

 

[taliv]

i've seen more malfunctions than i can count on the value brands at classes and matches. vast majority of issues were BCG or chamber cut related. I've seen several lugs sheered and broken bolts. handguards shift and bind the gas tube, gas blocks move, bent charging handle

 

[GBExpat]

...

 

[Varminterror]

I have a Bushmaster Hbar M4gery which has to have 40,000-50,000 rounds on the receiver. Two FCG’s (just upgrading, but technically added service life via preventative replacement), replaced bolts, bcg’s, gas blocks, & gas tubes with barrels every 5-8k, replaced buffer spring every 5-8k. Haven’t had any failures in it. It’s a garbage disposal. Cheap rifle at the time. Relatively.

Good barrels, good bcg’s and bolts, staking/pinning/loctiting everything which needs staked/pinned/loctited, and replacing consumable parts as they come due seems to keep them happy. I think a lot of the spare parts we see guys keep around aren’t valuable. I have never broken an AR firing pin, and never had an issue with gas rings. Gas blocks come loose if not pinned, especially if not loctited, and bolt lugs break. I’m pretty persnickety about what handguards I use - for the exact reasons @taliv mentioned. Never happened to mine, but I have seen guys knock a cheap freefloat tube off and bend their gas tubes (of course, 200-250lb dudes banging into barricades will stress a handguard).

One thing I do which I believe helps to ensure good bolt service life is lapping the bolt lugs to ensure high contact. I have seen rifles with only two lugs touching - and naturally, having such little load distribution can’t be good for the lugs.

My bro-in-law had a DPMS Sweet 16 he brought to me after it started failing to cycle sometime after a hundred rounds or so. When I got it out of the case and pointed the muzzle down to carry it into my shop, the gas block slid clear off the end of the barrel. I dimpled the barrel and ran red loctite on the set screw, never slipped again.

He also built an Aero/Odin/cobbled together thing, then couldn’t get anything to feed, and the bolt wouldn’t close on a lot of rounds and misfired on even more. The hammer was closing the bolt carrier into battery, which gave light strikes, and his extractor bevel was too short, so his bolt would dead stop against the case, instead of snapping over. Of course, this all happened on Day One, so once he brought it to my shop and I tuned it, it hasn’t had any issues since. Wasn’t really a cheap rifle, wanna say around $1,000 in parts?

Broken bolts happen. Part of the game. A dude on my squad at a match in TX last month had a lug break - he dropped in a new BCG and picked up the next stage. Also wasn’t a cheap rifle, precision built AR-10’s aren’t cheap. At the same match, another guy with a NEMO Omen had his forward assist come rocketing out of the upper - broke the retainer pin and broke the indexing pawl. Only way I figure that could happen was the pawl was a little too long from factory, or he got gunk in the FA bore which held the FA forward when it fired (or held his thumb against the FA when shooting free recoil), and it was snagging the BCG notches) just enough to eventually cause failure. That’s something like a $5k rifle if I recall. Not sure on the round count for the rifle. Ran fine before, during, and after, just had to replace the FA assembly.

Had a case rupture in a Bushmaster Varmint Special, blew the mag out, had to replace the mag catch, the mag, and my underwear, but everything else was groovy.

I did have a Colt gas key screw break on me once, gas key went loose, didn’t want to fully eject. High round count. New BCG, rather than trying to EZ out the broken stub.

The ONE thing I would say is a common problem for cheap AR’s or cheap AR parts kits is the grooves on the FCG pins are too shallow, so the pins walk out of the receiver at one end, and the FCG’s get sad. A couple minutes with a triangle file to clean the grooves a bit and it never happens again.

 

[Coal Dragger]

My worst example is a CMMG.

The barrel had to be replaced when the chrome lining started to flake out of it, after maybe 250 rounds. Inspection of the barrel once I pulled it revealed that the crown appeared to have been unfinished as well, looked like a half hearted high school shop project. The gas key on the bolt carrier was also improperly staked and worked itself loose in this 250 rounds, and ended up chewing up the gas tube and resulting in short stroking. So on the upper we have one parts failure so far, and improper assembly resulting in parts failure in 2 other areas.

The lower receiver the monkeys at CMMG managed to put the castle nut on the receiver extension on backwards. The fire control group has been reliable although the hammer spring is weaker than my Colt, Daniel Defense, Geissele, or Knight's Armament counterparts.

I've also witnessed friends have issues with two Rock River Arms AR's and one Bushmaster. In all the .223/5.56mm examples the problem is chambers that are way way too tight resulting in feeding issues, I remain firmly in favor of a properly cut 5.56X45 NATO chamber; all of mine are equipped that way and the Colt, DD, and KAC barrels all shoot very very well and run 100%. In fairness both Rock River and Bushmaster were responsive in correcting the issues, but they should not have been issues to begin with.

I witnessed a classmate in a Pat McNamara class have a host of problems with an older Bushmaster, all improper assembly related though, no parts failures. The same class I witnessed a shooter take a brand new Colt LE6920 out of the box and blue wrapping plastic, run a bore snake down the barrel, lubricate the BCG generously, slap an Aimpoint on top, attach a sling and run it for the class..... talk about shaking your gear down in a high round count class. The Colt ran superbly for him BTW, zeroed easily, shot good groups, and cycled everything he fed it without complaint from Gen 3 PMags. Other shooters were running Colt's, BCM's, I ran a Daniel Defense, the aforementioned problematic Bushmaster, and one shooter ran a Rock River Arms. The Rock River Arms had some issues related to the shooter's suppressor coming loose and getting baffle strikes..... kids: direct thread suppressors have no place on a high volume of fire applications in my opinion one other shooter ran suppressed and his can was a Surefire on an adaptor that was rock solid. Spend the extra coin, get a suppressor that attaches to an adaptor for your AR.

 

[94045]

In my experience, inexpensive ARs that have problems are usually built incorrectly.


Misaligned gas blocks. Springs installed in the lower improperly. Kitchen table trigger jobs. Improperly torqued barrel nuts.


A friend of mine bought some no name cheap lower parts kits from some no-name distributor on ebay. The springs were JUNK and his rifle was a single shot. I gave him a spare mil-spec FCG that I had laying around and cured his issues.


My 'cheap' build where the barrel is a PSA Freedom 1-7 4150 CMV Nitrided barrel, and the bolt carrier group is one of their premium BCG sourced from Toolcraft.

About 2k rounds through it so far, which I don't consider to be high round count.

View attachment 810707


My 3-gun rifle has about 10k rounds through it. Original bolt and barrel still. DPMS 416 Stainless MK12 barrel, CMT/Stag HPT/MPI tested bolt.

View attachment 810708


I call them cheap because I pick and choose parts based on my perception of value. I'm not interested in a rollmark, but in how a rifle performs.



I haven't broken a bolt yet. It won't surprise me if I shear a lug in the 3-gun rifle. I scoped the bore and there is a LOT of flame cracking and erosion. I don't know how much accurate life is left in it. I will retire the bolt when I retire the barrel. Maybe another season? It is heavy but it shoots very nicely.

My cheap AR is pretty similar to yours. Same barrel (Except 1:8) and same Boron BCG.

2000 rounds and still groups 75 Grain Gold Dots into one ragid hole at 100 yd. 0 function issues with Metalform Mags and no parts breakage. It doesn't like Pmags.

If your going cheap, do it yourself. Your quality control will be better than a Mid-Level Manufacturer and what you learn will be invaluable if you have to troubleshoot an issue. Spend targeted money on decent parts like a Good BCG and it's better to buy a budget Melonited/Nitrided Barrel than a cheap chrome lined barrel in my opinion. The cheapest chrome line barrel I would consider is FN (If you can still get them).