so I've been noticing the last couple of trips my ar has been having some weak ejections issues, they usually kind of trickle out at the 1'oclock position. I changed the extractor spring hoping it cure the problem but to no avail. the issue has actually seemed to be getting worse resulting in a few failure to ejects today which I've never had happen in my gun. i threw my friends colt 6920 bolt in it and still had the problem so I'm guessing its the gas or buffer system.

spec on the guns- dpms ap4, less then 2000 rounds through it, ARMS 41b silhouette front sight and gas block.

i thought it might have been the gas block but it has run great since being installed in december so i don't know why it would act up now
next i checked the gas port itself because i did run a .22 conversion in it a couple times but i didn't see any leading in the port but used a pick and try to remove any lead that might've been in there

so at this point I'm trying to see what to try next, any help would be greatly appreciated i love this gun and want to keep it running strong.

so I've been noticing the last couple of trips my ar has been having some weak ejections issues, they usually kind of trickle out at the 1'oclock position. I changed the extractor spring hoping it cure the problem but to no avail. the issue has actually seemed to be getting worse resulting in a few failure to ejects today which I've never had happen in my gun. i threw my friends colt 6920 bolt in it and still had the problem so I'm guessing its the gas or buffer system.

spec on the guns- dpms ap4, less then 2000 rounds through it, ARMS 41b silhouette front sight and gas block.

i thought it might have been the gas block but it has run great since being installed in december so i don't know why it would act up now
next i checked the gas port itself because i did run a .22 conversion in it a couple times but i didn't see any leading in the port but used a pick and try to remove any lead that might've been in there

so at this point I'm trying to see what to try next, any help would be greatly appreciated i love this gun and want to keep it running strong.

Is the gas block one with 2 screws in the bottom snugged up to the barrel?

#1 problem can be you didn't use red locktite
#2 problem is you didn't drill dimples in the barrel for the screws to prevent the block from twisting

If the block is no longer lined up on the gas vent, you may not be getting sufficient blow back to the bolt.

If the block is pinned, then it's something else.

i used blue loctite might try red next but i not sure it will make much difference though with all the heat while firing. also the gas block has horizantal clamp screw so i don't know where drilling a dimple would've helped. 

i used blue loctite might try red next but i not sure it will make much difference though with all the heat while firing. also the gas block has horizantal clamp screw so i don't know where drilling a dimple would've helped.

May want to verify the gas vent is aligned first.  If that's the problem, then the remedy will be to follow the gas block's installation instructions exactly and make sure it's not going to loosen again.

Good luck!   

Check the entire gas system front to back.

Also check the alignment of the gas tube into the gas key.

Bring it in if you cant figure it out

I dont recommend red locktite. There are other ways to secure the set screws.

After looking at the sight/block device, it would be obvious if the block had rotated because you would have lost zero for windage.

So, unless you've been adjusting the windage for no known reason since December, it would have to be a something else.

Have you maybe started shooting .223 ammo, but were shooting 5.56 before?  Changed brands of ammo?

Have you maybe started shooting .223 ammo, but were shooting 5.56 before?  Changed brands of ammo?

This would be my guess, or have you messed with your buffer system i.e. different buffer weight or buffer spring other than what was stock?  If you have, the change in ammo from 5.56 to .223 could produce similar issues that you are experiencing.  IMO you can't go wrong with taking it to X-Ring to have them take a look too.  A second pair of eyes never hurt anything.

so I've been noticing the last couple of trips my ar has been having some weak ejections issues, they usually kind of trickle out at the 1'oclock position. I changed the extractor spring hoping it cure the problem but to no avail. the issue has actually seemed to be getting worse resulting in a few failure to ejects today which I've never had happen in my gun. i threw my friends colt 6920 bolt in it and still had the problem so I'm guessing its the gas or buffer system.

This is likely a gas system related issue.  When you swapped in your friends parts did you swap just the bolt itself or the entire Bolt Carrier Group?  I might think it would be ammo related but if you are consistent with ammo and the situation has gotten progressively worse with time that would generally rule out ammo.  Normally I would check the claw of the extractor plus the extractor and ejector springs but again if the Colt bolt performed similar I would move on to the rest of the gas system.   

Some possible or more likely issues.  Starting from front to rear.
- gas block misalignment
- leak around gas block (gas block clamp came loose)
- gas tube misalignment which causes the gas key on the carrier to slowly file down the bell end of the gas tube causing a progressively worse leak.
- gas key coming loose
- gas key opening getting worn where it meets gas tube
- worn gas rings (not as likely if you tried a different bolt, unless other bolts gas rings are bad also)

Of course it can be related to other issues but these are more likely the areas to look at first. 

Also a simple way to check the buffer and spring is to slap your upper on your friends 6920 lower.  Also swap out you entire BCG for his BCG.  This will greatly narrow down the possibilities. 

Also fwiw, DPMS rifles are overgassed from the manufacturer.

Thanks for the in put guys, I've ran both 5.56 and .223 and didn't notice a diffrence. I'll be sure to give my whole gas system a good look through. I haven't changed the buffer system at all so I hope that rules that out. I'll take apart my other AR and make sure that the gas tube and what not are similar and look for any possiable issues that you addressed surf. I'm really hoping it was just a matter of the gas block shifting over.

When you fire the last round, does the bcg lock back?

Yes bolt locks backs every time on the last round. I pulled apart the whole gas system and didn't see anything out of place. Is there a way to insure the gas block is on directly over the gas port aside from eye balling it?

Yes bolt locks backs every time on the last round. I pulled apart the whole gas system and didn't see anything out of place. Is there a way to insure the gas block is on directly over the gas port aside from eye balling it?

If you had the kind of low profile block that uses set screws tightened into dimples in the barrel, there are tools for ensuring exact alignment between the gas block and barrel vent holes.

Easiest way I've found is put a rubber tube or something similar over the muzzle and make an air tight seal.  Blow air down the barrel, and move the block front to back & left to right.  You'll feel the resistance increase when the vent is not aligned, and much less resistance when in alignment.

Another way is to make a mark on the barrel where the center of the vent hole is, a mark that is visible when the block is in place.  Do the same on the block, marking the center of the hole.  Line up the two marks and the holes are good left to right.

What kind of handguard do you have?  When measuring for front to back alignment, most good low pro blocks are made to go all the way back to where an A2 handguard ring would sit.  For your block, it's designed like an A2 FSB.  You probably need to leave a gap between the block and that stop on the barrel where an A2 hand guard ring would normally be.   If you ARE using an A2 style handguard, then it should be in the correct spot already.

This is all from my limited research and experience.  I've installed 4 low pro blocks and changed the handguard to a free float style.  Without having used your specific block, this is a close as I can get.