I just put a JT CAR kit together with a Bushmaster lower. Everything works great except that when I push the bolt catch to load the first round, the bolt doesn't go all the way forward. I have to hit the forward assist and then no problem--I can empty the mag without another jam. What could be causing this ? I am using orlyte mags. Thanks for any information anybody may have on this problem.

I am guessing that you have a fully loaded magazine (20 or 30 topped off) and that is your problem. Most people load two less than capacity to prevent this problem.

I have only loaded 10 rounds in the mags(30 rounds). Maybe something else is causing this?

Pull back on the charging handle, and then ride it forward.  The hammer may be stick on the firing pin (will need to lower the top of the contact pad), or the hammer tail may be too long and the hammer is binding up between the disconnector and carrier (look for a wear mark behind the hook).

If you find neither is the problem, check the feed lip/front lip of the mag to see if it has a bur that is holding up the ammo in the mag.

Kinda sounds like my Bushmaster when it was new.  However I noticed that I could feed a fresh round and the pull it out and it would have two deep grooves cut in to the bullet jacket.  The corners of the locking lugs on either side of the feed ramps were cutting into the bullet.  My solution was to get some 2000 grit sandpaper (in the automotive dept at Wal-Mart) and cut a 1" x .5" piece and wrap it around the head of a bullet.  I then used the sandpaper wraped bullet to dull the corners of the locking lugs by running it between them as if the round was feeding in.  Now it feeds anything even Wolf in a full 30rd mag! [^]