I realize that this is the millionth FTF topic, but I think the problem I am having is a little different than a couple of the others I have read and I didn't want to hijack someone else's thread to resolve my issues.

Rifle specs are as follows:
18" Schneider Poly Bore barrel
Badger Gas Block
A3 Upper
Bushmaster Lower with A2 Stock

The upper was professionally done (GA Precision) and the lower was complete from Bushmaster.  For my first AR, I didn't want to monkey around too much.  Here are the problems I am having.

1 - The first 5 or so rounds will fire and cycle the action properly.  After that, the rifle will fire, extract, and eject, but will not feed the next round.  I have to manually cycle the action with the charging handle, then the process repeats.

2 - Out of a 30 round magazine, I seem to have at least 2 FTEj where the bolt will be about half to 2/3 the way back in the upper, I can see the spent casing completely out of the chamber, but it appears to get "hung up" mid cycle.

This happens with White Box 62 grain, Federal American Eagle 62 grain, Federal Gold Medal, and Hornady Tap 75 grain loads.  Magazines are all LeBelle 30 round capacity, new with the exception of 1 Bushmaster 10 round magazine.  All magazines I have tried give the same results.

Interestingly, the bolt will hold open on the last round of the mag every time I try that function test.  Also, if I hold the upper on a 45 deg angle and drop the bolt, it will close on an empty chamber and lock.

I'm stumped fellas.

Thanks in advance for any help.

I had a similar problem once, polished the chamber and the problem went away.  I was told that the slightest spur or burr will "hold" a fired case for a split/fraction of a second causing the bolt to loose some of it's rearward energy.  Thus, the bolt does not come back with full authority.

That could be it, especially on a brand new custom barrel.  What did you use to polish it?

Allow me to correct myself....  I did not do it personally, I sent the barrel back to Bushmaster who did it for free.