DPMS AR 15 bolt not closing

[bulletstuffer]

This just started happening.  Bolt slides like a hot knife in butter when working the action by hand and works fine that way.  When fired the empty is ejected and the bolt stops at 2/3rd of the way closed.  Any suggestions would be appreciated.

Thanks,

Bulletstuffer

[Bigeasy]

Bad ammo?  I''m assuming the gun is clean with no carbon buildup in the action.

Larry

[shvlhead.45]

With out hands-on trouble shooting it's hard to know exactly but if I was encountered with the problem you are saying you are having I'd check and ensure there is nothing in the chamber (piece of a ruptured cartridge case left in the chamber..., try different magazines as it could be caused by a defective magazine, shot gun it and ensure that the bolt and carrier group will completely lock when held to the rear of the upper receiver and dropped and that carrier key is correctly aligned with the gas tube, ensure bolt rings aren't worn excessively by setting on a bench or table top with the bolt face down and if the carrier drops when you turn loose of the carrier the rings are worn out and would cause a short stroke, ensure that ring gaps aren't aligned,  and ensure the ammo in use will drop in chamber freely especially if it's hand loads.  If using the cheap russian ammo with the lacquer coating, make sure that your chamber isn't full of the lacquer as it will melt off the cartridges when firing.  If a new upper or barrel has been installed, ensure that there isn't a lip between the barrel and receiver where the feed ramps are.  Hope this gets you shooting again.  One question, will the partially fed round chamber and lock with a couple of taps on the forward assist?

r/shvlhead.45

[bulletstuffer]

The bolt is very clean and we tried the magazine swap.  Used a couple of different types of ammo but all reloads.  The bolt stops about a full inch from closing with the live round rattling around in front of the partially closed bolt.  I don't think it would be the ammo but then again that's why I'm asking.

Thanks,

Bulletstuffer

[teddy12b]

I had something like this with a Bushmaster 20" Hbar model after shooting some silver & brown bear ammo.  Take a really really hard look at your gas rings.  When mine was doing this it was because one of the gas rings was half worn off.  I sent the upper into Bushmaster and they took care of it, but that still shouldn't happen in the first 500 rounds.  How many rounds are through this gun?

If I flick out my bolt and set it on the table, the weight of the carrier will close it and my rifle isn't malfunctioning anymore.

[bulletstuffer]

Round count is around 3k and a bunch of wolf ammo went through it when it was new.  I will check the gas rings.

Thank you ,

Bulletstuffer

[S.S.]

sounds like a typical AR to me?


   I just had to, I could not help myself

[jmayton]

First, clean your chamber. . .really, really well.  Then, since you're shooting reloads, turn your sizer die down until it touches the ram and then turn it down so that the handle will just "break over" when you size.  It's usually about 1/8-1/4 turn. . . maybe more.  If that doesn't work, then get a small base die.  I had the same problem and once I turned my die down, everything worked fine.  It just a problem with autoloaders and reloads. 

If there is something wrong with your bolt and/or carrier, do yourself a favor and put a Daniel Defense BCG in there. . . DPMS BCG's are not mil-spec and will not hold up as well as a mil-spec BCG.  Don't buy into all the super high-end bolts out there, just put in something that works.

[Lloyd Smale]

switch to a small base sizer die.

[jmayton]

Lloyd, you're right, but when I first had the problem I called RCBS and they told me about screwing the die in further and to try that first.  Since then, I've had no problems. . . but if it started doing it again, I'd get a small base die.

[Savage]

As Lloyd said, save yourself some grief and get a small base sizing die. When loading ammo that MUST function in any rifle of the same caliber, you learn this quickly! And by all means, get out the old chamber brush and clean the chamber properly. Very important on an AR. If the above doesn't work, check your buffer spring and tube for damage or binding. Good luck!
Savage

[teddy12b]

I'm getting a little rusty on my reloading die knowledge, but I always thought that the full length resizing die was the one that allowed the loaded round to cycle in any gun of the same caliber not the small base die.  I load all my ammo on full length resizing dies and it works well from gun to gun.

[jmayton]

Most FL sizing dies to not resize the base enough to be completely reliable in some autoloaders.  It varies from gun to gun.  Sometimes, all they need is a bit more push into the die (my case) and sometimes they need the small base die.

[Lloyd Smale]

I load all my ar ammo in 223 and 308 with a small base die. There the guns that might be called on to defend my family and reliability comes first. Using a small base die and triming after every firing insure this in an ar. If yo use once fired brass and dont use a small base die i can guarantee you that your eventually going to run into brass that isnt sized down enough. Ive tested alot both ways and really cant see a differnce in accuracy doing it and its no more work so its a no brainer to me

[jmayton]

Lloyd, my AR is more for competition and hunting.  If I had to defend the home, my first choice is a 12ga.  I completely agree with you, but have so far had no problems with my method.  I actually needed some cheap rounds for a competition and didn't have a lot of time.  I had resized a bunch of brass but hadn't trimmed it yet.  I just ran it through anyway and had no problems. . .but then again, I have a Colt 6920 and has run with all kinds of filth on it and in it.  When my friends with DPMS or Bushmasters have problems with their rifles I understand why mil-spec matters.