Reliability testing

[watercop08]

I tried to find a thread on this topic with the search function but came up short.

When evaluating an AR what standard are you guys using to deem the rifle reliable?

I ask because I have an 11.3 upper that locks back intermittently on an empty mag when fired off the shoulder. Firing from the shoulder has shown 0 malfunctions over the course of approx 1000 rounds.

To test this upper I gathered sever types of ammunition and magazines and headed to the range. Initially I found that the rifle would not lock back reliably when holding the rifle loosely with the stock off the shoulder with 55gr Pmc .223, 55gr Ae 5.56, 55gr wolf gold, or 55gr federal tru soft point .223. I used a mix of usgi w/ magpul followers, magpul, and lancer mags of various age.

After the initial test I inspected the upper and found the gasblock was canted very slightly to the left but was still tight. I noted no signs of gas leakage. I disassembled the upper and reinstalled the gasblock. I noted that the tattoo mark under the gasblock was centered around the gasport.

Second trip to the range with the same ammo and mags resulted in only 2 failures to lock back over the course of 30 rounds. Instead of failing to lock back at all the bolt catch missed the bolt but engaged on the carrier. For both test 1 and 2 the temp was a mild 70 degrees.

Last week I conducted a third test with ambient temps at 5 degrees. I let the rifle, mags and ammo cool of to the surrounding temp and ran through 30 rounds of 55gr federal tru.223 stopping every 10 rounds to let it cool back off. The third test yielded one failure to lock back by locking on the carrier and not the bolt face.

The rifle was clean and well lubed for all 3 tests. Ideally I’d like 0 failures to lock back since this is intended to be for duty use. Anyone else have a better method of evaluating?

Aero forged upper
Ballistic advantage 11.3 Hanson barrel
Pinned gasblock
Noveske kx5
Noveske phosphate bcg
Griffin armament rigid rail
Bcm charging handle
Standard m4 toe recoil spring
H buffer

[vicious_cb]

Is this a new gun? How many rounds total through the gun? It would help to put a few hundred rounds through the gun before doing any lock back testing. The contact surfaces need a few hundred cycles to wear into each other. Never mind saw it was ~1000 rounds :rolleyes:

You can try a lighter buffer weight one step down from what you are running now if you are concerned. But honestly, PMC is very weak ammo. If my gun is barely successfully passing the off the shoulder lock back tests with weak ammo then I consider the gun optimally tuned for 5.56 pressure ammo.

[watercop08]

First test was new, second test was at approx 300 or so rounds, third test was post 1000 rounds. I should note the lower is an m16a1 lower with what I assume are original lower parts.

[MegademiC]

Edit- missed the info at the bottom of op somehow.

Id try a carbine buffer. Testing method sounds ok.

As CB said, may need some rounds to wear in bcg and seal any gas leakage, especially with a custom build.

I would tailor the gun to your duty load (556 vs 223).

[vicious_cb]

First test was new, second test was at approx 300 or so rounds, third test was post 1000 rounds. I should note the lower is an m16a1 lower with what I assume are original lower parts.

Well it makes sense you are getting less and less failures to lock back as the contact surfaces wear into each other. It will only get better from there. I would pick a proper 5.56 pressure duty load and go from there. I wouldnt care too much if my gun was barely running on weak ammo as long as it functions 100% on my SD/duty load.

[watercop08]

Unfortunately policy limits me to the federal 55gr tru soft points for duty use. I used the federals for the most recent test.
1 out of 30 isn’t horrible but still not ideal. Pretty much chasing peace of mind I guess.

[Iraqgunz]

Your canted gas block is going to cause other issues such as premature wear of the gas tube.


I tried to find a thread on this topic with the search function but came up short.

When evaluating an AR what standard are you guys using to deem the rifle reliable?

I ask because I have an 11.3 upper that locks back intermittently on an empty mag when fired off the shoulder. Firing from the shoulder has shown 0 malfunctions over the course of approx 1000 rounds.

To test this upper I gathered sever types of ammunition and magazines and headed to the range. Initially I found that the rifle would not lock back reliably when holding the rifle loosely with the stock off the shoulder with 55gr Pmc .223, 55gr Ae 5.56, 55gr wolf gold, or 55gr federal tru soft point .223. I used a mix of usgi w/ magpul followers, magpul, and lancer mags of various age.

After the initial test I inspected the upper and found the gasblock was canted very slightly to the left but was still tight. I noted no signs of gas leakage. I disassembled the upper and reinstalled the gasblock. I noted that the tattoo mark under the gasblock was centered around the gasport.

Second trip to the range with the same ammo and mags resulted in only 2 failures to lock back over the course of 30 rounds. Instead of failing to lock back at all the bolt catch missed the bolt but engaged on the carrier. For both test 1 and 2 the temp was a mild 70 degrees.

Last week I conducted a third test with ambient temps at 5 degrees. I let the rifle, mags and ammo cool of to the surrounding temp and ran through 30 rounds of 55gr federal tru.223 stopping every 10 rounds to let it cool back off. The third test yielded one failure to lock back by locking on the carrier and not the bolt face.

The rifle was clean and well lubed for all 3 tests. Ideally I’d like 0 failures to lock back since this is intended to be for duty use. Anyone else have a better method of evaluating?

Aero forged upper
Ballistic advantage 11.3 Hanson barrel
Pinned gasblock
Noveske kx5
Noveske phosphate bcg
Griffin armament rigid rail
Bcm charging handle
Standard m4 toe recoil spring
H buffer

[NWPilgrim]

I would consider that totally unacceptable. I’ve used a variety of lowers but only BCM and LMT uppers, well except for one 20” range gun with a PSA sourced FN upper. I’ve never had any issues that were not ammo related over many thousands of rounds in each.

Whatever is wrong needs to be corrected and I don’t buy needs to be worn in. A decent rifle should function from the first round and absolutely should not be getting failures in less than a few thousand rounds. A duty rifle all the more so should be dead nuts reliable. I have not kept up with brands in the last few years. Is the upper assembly an off brand, or DIY? If it were me I would buy a seriously well reputed upper at least if not a new rifle just to be absolutely confident. I don’t know but Colt, BCM, LMT, KAC, DD, Sionics , etc. Some can be found at very good prices for the superior quality. Then spend hobby time trying to fix the current upper, which may turn into a rat hole.

[watercop08]

This upper is one I assembled from parts from the parts listed in the initial post. This was to replace the franken upper I was issued that sports a double star 4140 11.5 straight taper barrel that ejects consistently at 1'o clock (I'm a lefty so directly into my forearm/ wrist). My department does not allow personally owned rifles but due to my position I am able to change anything but the lower and fire control group. I also have to stay an 11.5sih barrel and the noveske pig or a suppressor.

I should mention that after reinstalling the gas block it appears to be centered.

[mark5pt56]

Don't take this the wrong way, but I would buy a factory gun, one of quality and add it to the deductions next year.

[watercop08]

If I could do it over I would have just picked up a bcm 11.5 continuous taper barrel with the qrf rail but sadly it wasnt available at the time. I think I am going to do a forth test with a carbine buffer and see what happens. If it still isnt locking back reliably I think I will hit up Ballistic Advantage and have them take a look.

Does anyone do anything different when testing rifles?

update: based on Iraqgunz's comment I checked the gas tube and it does show signs of wear. I'll replace it and see what happens.

[ViniVidivici]

I know the bcg is Noveske, but we sure the carrier key is tight as well as gas rings?

[watercop08]

That is what I thought initially but I checked those and both are tight on the carrier.

[watercop08]

Update: Took the gun out in 5 degree weather against this morning and found that it would not lock back at all with any mag or ammo combination. while inspecting the gun I noticed it wouldn't lock back even if I ran the action with charging handle.

Once I got home I discovered that bolt catch had enough play in the channel that sometimes the follower would completely miss the tab on the bolt catch and other times it would only push it half way up. Replaced the bolt catch and the problem mostly went away but I experienced it one other time on a gen 3 20rd pmag. No other mags seemed to be affected.

Went back to the range and found that it still would not lock back on pmc (not surprised) but locks back every time on 5.56 AE and federal .223 TRU SP. During this second trip I experience a few failures to chamber when chambering a round from a lancer using the bolt release (easily remedied by tapping the mag). I suspect the Lucas Gun Oil viscosity at this chilly temp is robbing the bolt of velocity since I have never experienced this when running in warmer temps. Cold weather is quickly teaching my why immediate action drills are important.

[Dr. Bullseye]

Update: Took the gun out in 5 degree weather against this morning and found that it would not lock back at all with any mag or ammo combination. while inspecting the gun I noticed it wouldn't lock back even if I ran the action with charging handle.

Once I got home I discovered that bolt catch had enough play in the channel that sometimes the follower would completely miss the tab on the bolt catch and other times it would only push it half way up. Replaced the bolt catch and the problem mostly went away but I experienced it one other time on a gen 3 20rd pmag. No other mags seemed to be affected.

Went back to the range and found that it still would not lock back on pmc (not surprised) but locks back every time on 5.56 AE and federal .223 TRU SP. During this second trip I experience a few failures to chamber when chambering a round from a lancer using the bolt release (easily remedied by tapping the mag). I suspect the Lucas Gun Oil viscosity at this chilly temp is robbing the bolt of velocity since I have never experienced this when running in warmer temps. Cold weather is quickly teaching my why immediate action drills are important.

Someone already suggested a lighter buffer, right?

[watercop08]

Whoop, good catch. I forgot to mention I tried a standard carbine buffer but there was no noticeable difference.

[Iraqgunz]

Considering how that barrel is gassed, it doesn't surprise me. You have other issues happening.


Whoop, good catch. I forgot to mention I tried a standard carbine buffer but there was no noticeable difference.

[grizzman]

In the original post, it's stated that the gas block is pinned....yet you were able to eliminate the cant?

You also stated that it functions fine when run on the shoulder, but not when it's fired when not off the shoulder.
Have you been properly shouldering the rifle in the subsequent tests?

If this is a duty weapon, I'd stop all attempts to make it run and purchase a factory 11.5" upper.

[watercop08]

It’s becoming more of a “let’s learn from this” upper since it’s the first one out of many that I’ve assembled that has given me problems. It is also the first sub 14.5 inch gun I’ve thrown together.

I precieved gas block to be very slightly canted. I was only able to spot this after installing the rail and indexing it the upper using a one piece scope mount. So I pretty much eyeballed it, not exactly precise. But for peace of mind I reinstalled it. I used a BRD dimple jig and marker to index off of the gas port and place a witness mark under the rear set screw to give me another reference point than just the pin hole.

I have never had a malfunction with this setup while firing with the rifle shouldered. All tests have been conducted with the stock unsupported and the rifle held loosely.

[watercop08]

So played with the lower a little more tonight and discovered several mags that still don’t engage the bolt catch. I think this is part of the problem but not all of it since I am still having problems with pmc. I’m not worried about shooting pmc but more using it to replicate a less than ideal scenario. I figure if it will function with weak ammo it will when it’s dirty and dry (bad day). I think the barrel is slightly under gassed by design. My other Hanson barrels all run on whatever ammo I give them without issue; however they are not directly comparable because they are 16in mid’s.

The mags that do not engage the bolt stop are all gen 3 pamags and one early emag. Lancer, usgi and gen 2 pmags all work. I tested mags in the lower from the build in question and a second new aero lower.

Pics as soon as I can figure out how to post them.

[watercop08]

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[ViniVidivici]

Maybe grasping at straws here, but is it possible that lower is out of spec, as in the slot the bolt catch lives in is farther to the rear, closer to the FCG pocket, than it should be? So that it barely engages with some mags, but not others?

[watercop08]

I wound up checking more lowers and testing them with different mags. I found 2 aero precision and 1 lwrci lower that worked with the gen 3 pmags without issue. Including the previously tested colt m16a1 and new aero lower I have 2 additional aero lowers that fail, 1 Lwrc, 1 BCI, And 1 Anderson. The colt, first aero, BCI, and Anderson failed to engage the gen3 pmag followers at all while the lwrc and remaining 2 Aeros would function with some of the gen 3 pmags Allowed the follower to slip in front of the bolt stop but still had enough tension to raise the bolt catch into position.

I assume this is attributed to tolerance stacking but I’m not sure if it’s on the side of the mags, lowers or a combination. I wish I had more gn3 pmags to check. All of the lowers functioned with usgi, lancer, and magpul gen 2 pmags.

[Pappabear]

The mags you are using can be an issue as well. On my KAC SR15, I wouldn't get lock back on Colt 20 round mags, they have weak springs so I learned. Use Gen 3 Pmags if you have not. I ended up installing the beloved A5 buffer system to fix my issue. But I was running suppressed so that was another BIG issue.

What mags did you use and did it happen with all mags?

PB

[watercop08]

The gen 3 pmags are the ones I’m having problems with engaging the bolt stop. The pics are of gen 3’s and one older emag. There are also pics of the usgi and lancer showing they work in that particular lower. I think I’ll end up replacing the barrel with something a little more liberally gasses like the sionics midweight 11.5 or a bcm to take care of the low pressure issues and just not run gen 3 pmags in that lower.

[ViniVidivici]

I'm sure you could have a 'smith open up the port on that one, right?

[Dr. Bullseye]

It has to be something. Once I reinstalled my buffer and spring and did not make sure the spring "screwed" all the way to the top of the buffer. This made a huge difference in that it was harder to charge the rifle and maybe the buffer and spring were not depressing as much when fired. Could it be as simple as something like this?

[watercop08]

I called BA today and was told the gas port on the 11.3 is .070. I was considering replacing the barrel with a Daniel defense 11.5 so I called them them to see if it would fit the bill. I spoke with a DD rep who said they currently use a .069 gas port but older barrels with the previous .076 gas port may still be in inventory. I told both reps what’s going on with my current barrel and both suggested I may be asking too much of the .070 port size for my climate and ammo choice. The BA rep suggested opening the port to .073 while the Dd rep suggested .076. So my options are open the port to .073, .076, or leave it alone and shoot higher pressure ammo.

[grizzman]

I believe part of this thread's purpose was to determine how other members test their ARs for reliability, which I don't believe has been answered. I personally do not hold the tested rifle off my shoulder or in any other way to attempt to induce a failure. If I want to test it with less than full pressure ammo, I'll create handloads with mid-level .223 Remington pressure. If they run these, while using the weapon properly, especially in colder temperatures, when the weapon is dirty, then I can rest comfortably knowing it'll run under the same conditions with full powered ammo.

Since the rifle seems to function 100% when it's used properly (held to the shoulder) with all ammo tested, ignoring the magazines that I recall not working even when manually manipulating the charging handle, then it seems to have passed a reasonable test.


Have you tried swapping the bolt carrier group from another quality AR into this one yet?

[watercop08]

I believe part of this thread's purpose was to determine how other members test their ARs for reliability, which I don't believe has been answered. I personally do not hold the tested rifle off my shoulder or in any other way to attempt to induce a failure. If I want to test it with less than full pressure ammo, I'll create handloads with mid-level .223 Remington pressure. If they run these, while using the weapon properly, especially in colder temperatures, when the weapon is dirty, then I can rest comfortably knowing it'll run under the same conditions with full powered ammo.

Since the rifle seems to function 100% when it's used properly (held to the shoulder) with all ammo tested, ignoring the magazines that I recall not working even when manually manipulating the charging handle, then it seems to have passed a reasonable test.


Have you tried swapping the bolt carrier group from another quality AR into this one yet?


Thanks for the response. Initially I was after what method everyone else uses to test their rifles but it turned into more of a troubleshooting thread. I don’t mind the help trouble shooting but I am still curious what testing standards others use. I did try a bolt from my Daniel Defense middy but had the same result.