i am having ocassional feed problem with my m4gery, i have a cmmg/dpms upper with m4 feed ramps,i only shoot xm193 or imi m855. when it cycles after a round the next round is trapped in between the bolt carrier and beginnig of the chamber,  the stuck round has a ding on the tip of the bullet. can anybody give me some advice?
              thanks ,meat

Does it lock open on the last round out of the mag? Are you using USGI mags? Are the feed ramps smooth without any steps?

hey ,tweak
unfortunately i live in the peoples republic of kali. one of my mag is thermold the other is steel but not usgi. it does not get stuck in the last round. i have replaced the spring and replaced the follower with the green follower.
without the mag in , i can pull back on the charging handle and the bolt carrier closes fine.
it seems when i insert a full mag, and pull back on the charging handle and let go sometimes the round that is being cycled, the bolt carrier does not engage. its like a slow motion. and i have to push on the forward assist to get the bolt carrier to engage all the way.
still sound like a mag. problem? or is it just dirty. i have been cleaning it . if it sounds like dirt what kind of c.l.p. do you recommend.
i use tetra c.l.p. oh by the way my feed ramps have a little step how do i smooth it out?
      thanks, meat

Aftermarket mags can make any AR into a Jammomatic.  Get some USGI mags and see if the problem goes away.

If the USGI's will result in your going to club-fed, I have seen some 5 rounders made by O-Kay, and some marked "Colt".  They appear to be USGI quality. I would like to buy one or two, but the ones I have seen are going for 15 to 20 bucks each, probably to Kali?

The reason the mag is so critical is the top of the mag forms the feed system for the round to enter the chamber with the assistance of the bolt.  Just a small error in the shape, size, or dimension of the feedlip area is enough to stop the gun from feeding.

But, does the bolt lock open when the last round is fired?

If the feedramps aren't smooth, and by the bullet deformation I assume they are not, I would send it back.

tweak,yes the bolt does lock open after the last round.
        thanks , meat