Mis feed problems

[enigmatic]

Bushmaster Patrolmans......the bullet case will not feed all the way into the chamber, the bolt will not close entirely. Thisusually occurs after about 30 rounds or so.

Any clues?

[ryanek9freak]

Bad ammo? Or defective magazine.

[k2peaker]

Disclaimer: I am not an AR expert by any means. I'm on this site to increase my knowledge (I'm much more comfortable with handgun functioning). There are others that have forgotten more about ARs than I've ever known on this site, e.g., Hoser, ZakS, AlanS., theMillerBros (if they post here). But, your problem may be a pretty straight forward one to solve.

Per above post, definitely eliminate the ammo and mag variables, i.e., is it happening across multiple ammo types and many different mags?
What kind of jam is it? In other words, is the feeding round essentially lined up with the chamber but just not getting fully there? Or, is the nose of the round jamming up into the lugs. Info such as this would help the experts understand more of what you are seeing.

If you're still having the issue, try to determine if it is an overall cycling issue. Have a buddy watch to see if the bolt/carrier is fully cycling. If it's not, there can be a number of issues causing it. Assuming you're using a Milspec gas block & tube running "full open" (not an adjustable where the gas flow has been turned down), it may be worth looking at all the components that affect cycling (buffer spring, buffer weight, bcg weight, etc.). In a completely milspec AR, it should just be running as those components are usually selected based upon reliability first and foremost. I have issues when I'm trying to tweak for competition purposes, i.e., a lightened BCG. Anyway, some food for thought and request for more data on what you're seeing.
Good luck. Ken

[SA Friday]

Absolutely need more info to determine what the actual problem is. First, 'at the 30 round mark' points to me to the last round out of the mag is not feeding all the way or the bolt is hanging up on a part of the mag. Have you tried more than one mag? If so, are they manufactured by different companies or all from the same company?

What kind of ammo have you tried with the gun? More than one type? Reloads and/or factory?

Have any modifications been made to the gun by you or anyone else? If so, what mods?

[Graves]

I would also recommend marking the mags and noting when, and which one has a malf.

[waxthis]

Is your gas key properly staked? If this comes loose it will cause havoc. Dont ask me how I know.....[Roll1]

[sagebrush]

U May Need A New Spring In The Stock....

[sniper7]

waiting on more information. is it just the last round in the mag? have you tried other magazines? what kind of ammo are you using? How old is the gun?