Hi all, just aquired my first and not last AR.
The dealer called it new but it has a Colt HBAR lower and a Bushmaster HBAR Upper. I bought a case of that South African .223 ammo and headed to the range. accuracy was good but out of 100 rounds I had three malfunctions.

It seems that after firing, the bolt would come back and instead of extracting the casing it would rip off part of the rim leaving the case in the chamber. After numerous attempts at removal, I had to use the cleaning rod to eject the round by pushing the rod throught the barrel from the muzzle end.

What gives guys (& gals)? Bad Ammo? Bad Rifle?
Any help would be appreciated.

Did that South African ammo have a lacqered coating? If so, when the chamber heats up, it start depositing the material in the chamber and acts like glue. This could be your problem.  

There is a warning at one of the factory websites. Either Oly or Armalite I think. Good Luck

Ammo is probably to blame. I shoot S&B laquered steel-case ammo all the time(cheap and accurate) and have never had even a slight problem with it. Oly arms uses SAAMI specs for their chambers, but Bushmaster goes by 5.56x45mm dimensions, so I doubt it's the rifle's fault. A Bushmaster (or Colt) chamber should accept just about any ammo you put in it, as long as it's good quality and in spec. Is the barrel chrome-lined? If not, it could be a barrel chambered to SAAMI specs, in which case mil-spec ammo may be too tight in it.

GlimmerMan,

Is the upper used? If so it is a possibilty that laquered ammo was used in it before and the chamber has accumulated a laquer buildup during periods of high heat.

Jake

The SA ammo, the 30 round box green battlepack stuff, isn't coated. Its a good, cheap ammo.

Jake

Thanks for the input guys.

The Upper, as far as I can tell is new. There is nothing to indicate previous use. The ammo I used was new and boxed 20 per box 10 rounds each in that plastic shell holder thing. I can't remember the name right now but it's like PMC but not. it's got some animals picture on the box.

I am going to try and shoot it again this week. I will post again if the problem persists.

thanks again

Try thoroughly cleaning your upper.  There may be some crud or heavy grease in the chamber that is causing the failure to extract.  I had a similar problem with a new upper I bought and cleaning took care of the problem.

Clean that baby real good and see what happens then.  
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