Adams Arms chambering issues

[Swobe1]

Hey all. I've always been a lurker more than a poster because I learn way more on here than I could ever share, but I need some help. I've had my complete Adams Arms 16" tactical elite rifle for over a year. I've shot probably about 1000 rounds through it with no issues until last weekend. Larry Vickers hardly makes it to Iowa so of course, my rifle started to fail to chamber completely. It ran fine every time I shot it before that. I cleaned it prior to the class and it was well lubed. I've emailed AA twice this last week with no response. And no, I don't need to hear about piston vs. di. I'm already ordering a BCM upper this week. This is what it started doing:

IMAG0150_1.jpg

Ammo was IMI/Samson 5.56 55 grain new, no reloads. This was out of a new PMag, but I had the same issues out of a new brownells mag, an old g1 pmag with different ammo, and another 20 round pmag with different ammo (not sure of the brand since people loaned me mags to try). Upon advice to change the extractor spring, I upgraded it to a BCM kit, still no luck. I have a 14.5" AA tac elite rifle also, runs great, no issues with this ammo, mags, or anything. I swapped bolt carrier's, same issues in the 16" with a different bolt carrier. This was not the first round, but after a few rounds fired, so it wasn't after bolt lock. It did again to me today with IMI ammo and Federal 5.56 ammo out of any kind of mag I have. Locking the bolt back and loading a mag then hitting the paddle resulted in this today:

IMAG0152_1.jpg

When this happened it was almost impossible to pull the charging handle back to clear it. I don't know what is going on. Sorry, I know I probably need to provide more info, but I've got mad twin boys who are trying to hi-jack my computer!!

[Iraqgunz]

What kind of buffer are you using? Have you measured the buffer spring? Is there some kind of spring in the front for the piston?

How do your bolt lugs and locking lugs inside the barrel extension look?

[Swobe1]

Both guns have the spikes t2 buffer in them, which on AA advice they should run just fine, which they have before with no problems. Other than that, I haven't changed anything in the operating system. I pulled the rod apart the day it started happening and cleaned it all one more time but it didn't change anything. I'll have to grab some pictures of the lugs.

[Iraqgunz]

Measure your buffer spring. If it is less than 10 1/16 inches, it needs replacing. I would also use a real H2 buffer, but that's really not the issue here. Does this set up have a way to adjust the gas? Could you have messed with it accidentally?

Both guns have the spikes t2 buffer in them, which on AA advice they should run just fine, which they have before with no problems. Other than that, I haven't changed anything in the operating system. I pulled the rod apart the day it started happening and cleaned it all one more time but it didn't change anything. I'll have to grab some pictures of the lugs.

[Leaveammoforme]

I think IG is onto it with asking about buffer spring and lugs. I say this because in your first picture if your buffer spring was strong it should override your bolt spring (bolt pushed back into carrier) with it as far forward as it is. Unless of course your bolt or extension lugs are jacked.

Couple easy checks in addition to above-

BCG standing on bolt face on table- bolt should not collapse into carrier. Genty push down carrier- bolt should slide in and then back out as you remove pressure.

Make sure your gas is in the 12o'clock setting.

Due to ski's on carrier- Lock bolt back, loosen extension castle nut and retighten. This will ensure straight shot for carrier into and back out of extension.

My AA upper material said it was set up to run on a standard carbine buffer & I have had no issues other than it not liking 20 round pmags.

[MistWolf]

...BCG standing on bolt face on table- bolt should not collapse into carrier...

I don't think this test applies to PIGB (piston in gas block) ARs

[Leaveammoforme]

I don't think this test applies to PIGB (piston in gas block) ARs

AA runs a spring on bolt tail to aid in bolt bounce. Spring in good shape will hold carrier up and 'grow' bolt back out as you release pressure.

[MistWolf]

That's different from "bolt should not collapse into carrier"

[Jwknutson17]

From my previous experience with my 2 AA uppers, I had mayor feed problems after about 600 rounds with one, and the other, the bolt carrier was binding in the buffer tube. I sent them both back to AA and they determined that both receivers were out of spec. They both came from Midway during the "scare". They replaced the upper receivers on both, and I didn't have any issues afterwards. But they both would not run 100 percent on anything other then a Carbine buffer and spring with the piston in the 12oclock position. Your issues could be completely unrelated to my experiences, but I would send it back to AA. They will take care of you.

[USAF1980s]

I agree with above, contact AA and they will inspect upper.

I have 4 AA uppers (varying lengths) on NFA SBR/M16/Pistol all GI spec lowers. No issues like you have experienced.

I run a Viltor A5 with Viltor A3 weight buffer on the NFA M16 lower (it did not really lower cyclic rate BTW). Run H2 (Spikes T2 or regular H2) with standard spring (CS) on SBRs as well as pistol (Spikes extension tube/SB15).

I have a collection of springs and buffers to aid in diagnosing friends AR issues but the H2 and standard spring has been fine for all AA uppers.

If you wanted to test your upper/lower and extension fit, you could remove your hammer (eliminate hammer drag on BCG) and remove buffer spring/buffer and see if there is binding of the BCG in the extension.

One thing I have noticed is that the AA uppers are not radius-ed in the 2 M4 feed ramps and barrel extension. I have done this with a few uppers to eliminate marking the brass (putting scratches on neck of case). After slight removal of the sharp edges, the feed seems a bit smoother (by hand, dummy non-loaded ammo) and no marking on the spent case. I don't think this IS your issue, but may contribute (picture 1 has the cartridge just entering the chamber at the ogive...there a bouts and is past that issue as a factor).

My first guess is a bad buffer spring, 2nd is extension alignment.

Let us know what you found.