Warning

 

Close
Confirm Action

Are you sure you wish to do this?

Cancel Confirm
AR15.COM
AR Sponsor
7/29/2013 5:07:35 PM EDT
Hi guys, new to the sight. I just built my first ar. It is a dpms lower, aero upper, yhm 14.5 diamond fluted barrel. Took it out to shoot it for  the first time last weekend and it  shoots, ejects but doesn't feed. I am thinking the buffer is to heavy or the spring is to tight. It doesn't seem like it is bringing the bcg back far enough to load the next round. I am was shooting XTAC ammo. I'm not sure what buffer weight is in it , because I bought the buffer tube, spring and buffer as a "kit" from psa. Do you guys think I am correct on the buffer being the issue?

P.s I tried 3 diff pmags.
7/29/2013 5:11:55 PM EDT
[#1]
PSA buffer kit is -likely- a standard weight buffer.  What length is the gas system?  You may want to run down a list of all the small parts to save on questions :). I shoot x-tac 55gr a lot and I doubt it's an issue with ammo alone.
7/29/2013 5:14:18 PM EDT
[#2]
It is a carbine gas system, troy gas block, lmt bcg
7/29/2013 5:17:16 PM EDT
[#3]
What type of gas block do you have on the barrel?

If it's clamped on the alignment could be off.

If it's clamped or pinned, there's a chance here is a minor bur in the gas port from machining that's restricting gas from entering the FSB.

Wes
7/29/2013 5:18:20 PM EDT
[#4]
Carbine gas, xtac, and even a heavy buffer doesn't seem likely to cause cycling issues on parts alone.  Something is definitely up.  
7/29/2013 5:19:12 PM EDT
[#5]
Ok, I will try taking it all apart and check my alignment before I try a different buffer Config.
7/29/2013 5:39:18 PM EDT
[#6]
Did you load 1 round in the mag and see if the bolt catch is catching and locking the bcg?
7/29/2013 6:08:12 PM EDT
[#7]
DId you lube your BCG?

You may just need to run it "wet" and give it a chance to break-in
7/29/2013 10:44:20 PM EDT
[#8]
Did the barrel have a dimple under the gas port?   Gas block may be to far forward or to far back and not getting proper alignment.
7/30/2013 2:50:19 AM EDT
[#9]
Yes I did lube the BCG pretty good before I fired it. No there was not a dimple in the barrel for the gas block. And yes I first fired it with 1 round an it fired good, but the BCG isn't coming back far enough to catch the latch and hold the bolt open. I'm going to pull it a part today when I get off work and check the gas block alignment. I will let everybody know! Thank you all for the help!
7/30/2013 4:26:29 AM EDT
[#10]
Something to keep in mind is that the barrel could be machined with room to install a handguard cap behind the gas block. If you are not installing a handguard cap, you may need to account for that thickness instead of just placing the gas block as far back as it will go on the barrel. Not sure if this is helpful in your case, but may be worth the time to take some measurements.
7/30/2013 11:06:53 AM EDT
[#11]
It is very unlikely to be the buffer.
It is more likely to be one of the usual problems with the gas system.
Look for things like a blockage, broken carrier key screws, misaligned gas block, leaks, etc.
There are other possibilities, but eliminate the usual ones first.
There seems to have been a lot of broken screws lately.
7/30/2013 11:11:14 AM EDT
[#12]
I went through this a few months ago. I had all mislpec parts by good manufacturers. I was so frustrated with the rifle. It would run on one guys BCG and his only. I never could figure out what it was. So I poured oil in the damn gun and single shot hand loaded 30 rounds with the charging handle. Finally it would shoot 2 rounds, then 3, then 4, now it runs strong... I checked the gas block alignment, buffer weights, buffer tubes, springs, bolts... I was about to give up. I am guessing it was all just too tight to run.
7/30/2013 3:21:01 PM EDT
[#13]
Just a thought but lean into it a bit more and hold on a but tighter.  My girlfriend has the same problem it short strokes every time but if I run the gun it runs flawlessly. I'm not calling you a girl but sometimes its not an equipment problem at all.
7/30/2013 3:26:44 PM EDT
[#14]
Is your carrier tilting and hitting the lip of the buffer tube?
7/30/2013 5:06:24 PM EDT
[#15]
Quote History
Quoted:
Yes I did lube the BCG pretty good before I fired it. No there was not a dimple in the barrel for the gas block. And yes I first fired it with 1 round an it fired good, but the BCG isn't coming back far enough to catch the latch and hold the bolt open. I'm going to pull it a part today when I get off work and check the gas block alignment. I will let everybody know! Thank you all for the help!
View Quote



This is going to be your culprit.   You most likely pushed the GB back against the shoulder on the barrel but you need space that would normally be reserved for the handguard cap.   there are ways to fix it but the best ways require acquiring a tool.  

I made something similar to this


When you take off the GB you might see a half moon mark around the hole in it that will show you the misalignment.
AR Sponsor