Help?? AR 15

[Frank4711]

My friends AR-15 jams, lower is a Rock River 5.56mm, upper is a DPMS 223 1-9 twist flutted SS barrel. Tried several diff mags, cleaned and only good 223 ammo, no wolf. Thanks for any help. Gun was bought used at gun show don't know history.

 

[DoubleTapDrew]

Your selector isn't all the way on fire, there's your problem
It may be a headspacing issue. Ran into that on our CAR-15.

 

[taliv]

can you be a little more specific on the type of malfunction?

 

[Frank4711]

Will not feed.

 

[7six2]

Does she cycle smoothly? Has the gas tube been checked?

 

[Frank4711]

No and No

 

[Bartholomew Roberts]

When you say will not feed, do you mean that the bolt does not cycle or that the round from the magazine stubs on the ramp? You say you tried several different mags. What type of mags did you try?

 

[Frank4711]

Mags are mil-spec aftermarket military. When clearling the jam there is most of the time one round in the chamber and one round jammed above bolt 1/2 open. Hope that helps, I shoot S&W revolvers , 22 mag pumps and a sweet FN PS 90, no jams here!!! Thanks Frank

 

[Frank4711]

Double/Triple feed may describe it best?

 

[SDC]

If it's leaving a fired case in the chamber and then trying to feed a fresh round in on top of the case, it's an extraction problem; clean the chamber thoroughly, see if there are any pits/gouges/etc. in the chamber, and make sure your extractor isn't chipped and has proper spring tension on it.

 

[Frank4711]

Thanks for the help!!

 

[Bartholomew Roberts]

Yeah, it is dropping the case on extraction. I'd look at replacing the extractor spring with a heavy duty extractor spring designed for a carbine. Good news is it is a cheap fix.

There is a phenomenon called extractor float where the extractor lifts on the case during initial extraction but is held to the face of the bolt by residual pressure. It sounds like your extractor is lifting off; but the residual pressure isn't strong enough to keep it on the face of the bolt. So my guess is something that gives the extractor more bite (o-ring insert, heavy duty extractor spring or both) may solve the problem.

 

[strangelittleman]

Yep, What Roberts said.
In the carbine length gas systems the extractors certainly are more likely to lift off the case due to the higher operating pressures of the short gas tubes. The operating parts are under more violent force than the full-length rifle gas systems, therefore they need the increased ex spring tension in order to hold on to the case head/ex groove more forcefully. When I purchased my Bushmaster Heavy bbl 16" carbine, I immediately placed an "O" ring and heavy-duty ex spring, but in my Altamont Tactical Outfitters' custom 20" A4 rifle, I only have the heavy-duty ex spring on the FN extractor & bolt and have found it works great.

Also, take a good, close look at your bolt carrier and insure the gas key is mounted properly, ie; flush to the carrier so that it has a good seal and make sure it's properly staked to the carrier also.

 

[Frank4711]

Thanks for all the help, it is appreciated. I will update with results.