Adams Arms 7.5 EVO Piston Upper - Issues running - Rounds not pulling from mag on follow up shot

I am having some issues with my new 7.5 Evo Piston upper.

I've read all the tacked and Adams Arms instructions.

This is built as a pistol and the lower was built by me.

This is a brand new upper on a Lauer MFG pistol marked lower with Mil spec parts kit and H2 buffer and spring assembly with Aluminum tube rear (I don't recall the length/make as I am at work). If I recall I think I bought the tube and H2 buffer for a pistol from Spikes. It is not the short buffer tube, but a longer one 6" possibly.

Everything was cleaned and lubed before I went to the range. I removed the BCG and cleaned it, but I did NOT disassembly the BCG. The piston position is on the #3 setting. (left to right, the one it is suppose to be on for semi fire). All of the piston components appear to be in the order the AA PDF shows them.

I have about 50 rounds through it. All 50 were hit or miss. Some would fire, then eject and reload and fire again, for the next one to not reload. Some would fire and not insert another round/reload. I tried three different mags (All aluminum) and all the mags functioned fine in my DI AR. Longest string of consecutive rounds was 8 in a row.

Ammo was a mix of hollow points/fmj - Federal, wolf, Remington, winchester (stuff I had laying around I wanted to use up for break in) (grain I am not sure).

Any ideas on what could be going on? Any chance the H2 buffer is to heavy? It almost seems like the bolt is not going back far enough to grab the next round from the mag. It does have the necessary travel to go all the way to the rear to pull another round.

Also I will note I have no added upgrades

Buffer is probably the issue. I run a stock carbine buffer in mine unless it is suppressed, then I use an h3.

Not to offend, but make sure the gas is on the right setting. I had a day of WTF due to that.

Fatkid

i believe the #3 position is single shot fire.

looking at the settings (with the barrel pointed at my face), the 9 o'clock setting is to remove the piston rod. the 12 o'clock is semi-auto normal fire, the 1:30 is suppressed, and the 3 o'clock is single shot.


here's from AA website faq:

Our gas block is set up with 3 different gas setting that are easily adjusted by pressing down the detent pin and rotating the gas plug either clockwise or counter-clockwise. The 12 o’clock position is the full or open position and should be used with normal fire. The 1 o’clock position is the low or suppressed position and is best used with a suppressor on the firearm. The last 3 o’clock position is the off position and allows your AR to fire without cycling the action.

I recall reading a thread about this last week and the majority of the problems went away once they switched to a standard carbine buffer. YMMV

mine is in the 12 o clock setting. #3 as I was calling it.

Trust me, I had a no brain - er on figuring out the settings, or I should say, there isn't a #4 gas setting. I should post the video in the fail gifs section.

I will swap in a different buffer and see if that works.

thanks

I will say and I should of said it from the get go.

This is a marvelous piece of craftsmanship. I've owned several AR's over the years and this upper is top notch.

I am very impressed with the fit and finish of the upper and the accuracy.

Grouping from the shots I fired even under emotion (saying why the hell does this not run right) from it not working and a temp of about 10 degrees out side with wind was about a 4" circle from 20 yards (standing offhand). Probably not the best shooting, but it was consistent where the lead was hitting on the target

Not to beat a dead horse I had the same problem on mine when running it with an h2 buffer. Went to carbine buffer and runs like a sewing machine. Over 8000 rounds and not a hiccup

i've been running the Spikes T2 buffers with all my AA upper and AAkits, so far they have been 100% but i also run quality brass ammo

The spikes T2 is 4.3 oz

The H2 I have is 4.7 oz

So the carbine guys are saying go with a 2.9 oz?

I use a carbine buffer and have no problems. I would recommend you use that one

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