I bought an AR15 from a friend of ours here on AR15.com and when I got it I took it to the range and shot it the only trouble I had was it didn't stay open on the last round and the bolt kept keeping the empty round inside and jamming the next one with it. I checked the ejector and it seamed to be OK. O yea this bolt is chromed by the way. I had my other AR15 with me so I took the bolt out of it it's just a black mil speck. put in the AR15 with the trouble and it shot and reloaded every time. So I put the chrome bolt in the other AR15 and it shot very well. I guess the RRA upper just don't like chrome!

RRA's never sold chrome-plated bolts, so your upper wasn't necessarily one of theirs.  Glad to hear it worked with the standard bolt.
Sluggo

I think the bolt came from some where else and was put in the RRA upper.

The extractor on the chrome bolt may be weak. and the chamber on the RRA barrel may be tight.

Just a thought..

Wierd[:D] Recently acquired a chromed carrier, and have tried it out in all four of my uppers; two Colt. one Rock River, and one (I think) Oly.  Worked fine in all of them. Must be some kind of slight dimensional glitch either in the carrier, or the upper; or maybe both.

I should have told you more about the gun. It's a cav lower with a RRA upper with a bushy barrel A Dissipater bushy fire controll sys and the bolt I have no Idea. Shoots very well right now but still goes closed on the last round instead of staying open.

1)Does it hold open when you use the non chrome carrier?

2)Will the bolt assy hold open when you manually open the action on an empty mag?

3)Does the other gun you tried the chrome carrier in hold open with the chrome piece in?

#1  It will not stay open with ither bolt in it.                                             #2   Only some times by hand if you yank on it.

#3   Yes the other gun holds open on the last round with both of them.

 Thanks for the help I'm kinda dumbfounded on this one.  Keith