??? HELP???

[Deleted]

Dec 27, 2012 17:12:17 GMT -8 abw said:

Dec 21, 2012 13:43:51 GMT -8 @sergiomartinez said:

Let me try to help you out.
First forget about the gas system for a second.
Did you try with another lower that is known to work reliably in another AR? Yes
If you try this and it works then you know other place where you need to look at.
One could say your system is under-gassed but before we draw any conclusions we also need to make sure the lower, magazine or the buffer are not putting the brakes on the carrier group.
Everything that happens in fast motion one can replicate in slow motion as far as charging the rifle slowing and looking for any frictions. The bolt should be unlocking very easily w/o obstruction. I would test this without and with the lower on. We have done this as well.
Then a hammer spring that has excessive force with a hammer that is out of spec or full of machine marks or rough cuts is going to slow down that initial push (I have seen them).
So while it is logical to start at the port I don't think it is a dwell time issue and before getting into any conclusions it is logical to follow the gas forces but not only looking for where gas pressure might be missing due to leaking or not being there in the first place but look at the internals and make sure there is nothing there slowing the group.
Charging an upper should feel very smooth and uniform force w/o any spots where it feels harder or slowing due to friction or other forces.
Make sure the bolt lugs do not make contact with the magazine lips due to dropping the magazine or something else. Nope
An adjustable block is going to do little for you as normally you use them to reduce the amount of gas.
Try cycling the system with M193 LC nato rounds that are pretty hot. But a well tuned AR should cycle with anything, even PCM bonce that are very mild.
Try this ammo and try another lower. if you want to call me send me a PM and I will be happy to discuss with you. Everything can be fixed the issue is to identify first where the real root cause is.

you welcome.

[abw]

Ok..here is where it sits. We had to drill the barrel.. Not enough gas..We open it and wham.. it worked. Thanks to BTE and BHW-Carl.. We then shot it several times going through 20 round and 30 round mags.. 1 bad magazine was found..

So we put on the new gas adjustable block from BTE and opened it up..I fired the rifle flawlessly first with 1 round in the mag..per instructions through 5 mags.. out of 6. 1 Bad mag..

I then did 5 -3 group shots to sight it in.. Locked back on every empty magazine. Sweet. Nice groups all within a circle of an inch. So I decide to just get er done. Load up a magazine of 10 rounds, then..it stop failed to eject.. did that for 15 more rounds.. different mags.. still fail to eject.. So back to armorer.. So close.. I believe at this time. It is ammo.. to go from flawless function..to crap.. has to be ammo. 55 gr .223. Remington umc..dirty..

It will get cleaned look for any other issues, and then i will fire BH 77 grain 5.56 it be week though.. If that fails I will call Yoda..

[GLSHOOTER]

55 grain UMC frequently appears to be light at times and reliability. Runs some GOOD stuff through it and you will be GTG I bet.

Greg

[abw]

That's what I am thinking.. When I got done and thou rightly irritated I looked at the upper through the ejection port and saw bits of unburnt, powder. I think it fouled all the working stuff up.. I got some .223 55 grain fmj from black hills ammo..factory new.. I will also run the agency stuff as well. The 5.56 77 grain..bh ..if that does not cure it's ills.. It ll be headed to Washington state..

I am seriously impressed with the accuracy..the first two groups I can place a nickel over and cover the both sets of three holes.. I have no idea what happened my last string of 3 but the are all in one inch circle centered -But no coin coverage other than maybe 50 cent piece.. ;D

once we figure out the issues in this last escapade I sure it will be gtg..that rifle will never see that other ammo again..when this things shoots right, it leaves me giddy..a rifle should not make me giddy..should it..