ETA Final: Found the culprit to all my problems. The gas block has cracked and failed right below the point of gas tube insertion. I can say that I ran just about 3750 rounds out of a 10.3" MK18 Upper. Range sessions included at a minimum 100 rounds and at least 40 rounds at a high firing schedule at which the suppressor would become extremely hot. The gas block & port resided at least 3.5" from the muzzle and suppressor.

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Could any of you do me a favor? The locking pin that secures the plate in place has a cut out notch that the torsion pin leg goes into. Is your notch facing up or down/1 or 2? Thanks

ETA: just so we are on the same page I am talking about the below, notice mine is facing up. Can you all confirm? Thanks @goloud @Dvalin_MT


Update: went through all setting .070 .052 & .082 without issue. I fired around 90 rounds mostly rapid on the .052 trying to get a failure like I had @ .049. No failures though and given what I have learned it would appear the back pressure from the can was too much for the .049 setting. All is well now.

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I have notches on both sides. I've seen plates without notches.

So, I don't think it matters. But I'd go with notches up. Shoots faster that way.

Notch facing down on mine.

Notch Up on my two

notch up on mine...

Thanks everyone. I have been trying to diagnose an issue and thought it was fixed after working with Amphibian. We had everything running fine against a 20 round test utilizing a spare .052 plate setting I had on hand after my .049 plate seemed to be causing an issue due to gas erosion. Amphibian sent me some new .049 plates and ran back into my same issue. I did not have this issue until i switched from a Gemtech GMT-556QM to a GA Recce 5 Mod 3. I had reinstalled and aligned the gas block using a drill bit so a misalignment issue,while could cause the problem, seems to be slim. All I can think of is that the Recce 5 creates to much pressure coupled with the .049 setting causing the locking pin to thrust forward enough to slide the plate out and between settings. I reinstalled the spare .052 plate and am going to do a 100 round test to see if it functions with no failure to confirm it is the can and not alignment.

I had read amphibian was taking time off to deal with family matters, surprising that he is still answering emails with questions. I may fire off an email here soon. my govnah equipped upper just decided to quit functioning after a couple thousand rounds, did about all the troubleshooting I can think of as well.

@vincentvega6 yes that is true, we actually communicated prior to his post announcing his matters a couple weeks back and stepping away. Which is why I am here troubleshooting with the hive.

eta: how did your upper quit functioning? What is your rifle setup and port sizes you were using? suppressed or unsuppressed

@NikolaFermi

after about 2500-3000 rounds it would not cycle suppressed on the reduced port size with the "mil spec" plate I had been running since I installed it. it would not cycle unsuppressed on the bigger size port either. it only runs on the big port size with the suppressor on it, gassy as hell and defeats the purpose of the block entirely. extremely frustrating. it will not reset the hammer or it will not cycle back far enough to pick up the next round on the smaller port. im running the geissele mk8 handguard so I only have room for the 2 position plates. 10.5" barrel 556, geissele super 42 H weight setup, silencerco omega with 556 flat cap.

I upped to the "extra gas" plate to see if it would rectify the issue, verified alignment with the drill/check pin per their website when it was up (I printed them previously so I had them on hand) and problem continued. I put new gas rings in it and it functioned as before for one mag. after that problem came back. put in a car buffer and spring and same issue. I hardly clean the gun so I took it apart and cleaned the unholy hell out of it. gonna put it back together and try some more trouble shooting. im going to swap the carrier to see if the gas key is at fault, I had read that some PWS DI carriers had issues with gas keys which is what im running. also gonna try heavier buffers and spring weights if the carrier doesn't solve the issue.

Is your plate moving out of place on the suppressed setting causing failure or is it still locked in place firm? @vincentvega6

My detent notch is UP.  

Vincent, I'm sending you a PM in a few minutes.

Correction:  I just sent you an email.

Update in op

update in  OP

That sucks. Are you going to try the SLR gas block?

Thanks for the update.

I am considering it as well as a gemtech or bootleg bolt carrier. The issues really brought home the means of controlling gas while keeping in mind that parts wear.

ETA: NemesisMind - No problem

Wow. Thanks fir that update and round count.