Took my AR to the range today. Problems right off the bat.
All new components except charging handle
Bushmaster 14.5 bbl with AK brake
Fulton A-1 upper
Fulton New G.I. bolt and carrier
The upper sits on an Oly lower that was used with a 16"  Oly upper. Never had any problems with it. No FTE's, FTEj's or FTF's. worked without a hitch.
I put the new upper on the old lower.
At the range I loaded one rd. of Q3131A. Fired and ejected no problem. Tried again, same result. Ok, so I loaded two rds. Blam. FTEj. FTF. WTF.  Tried again. same result.  Fired cartridge was extracted but not ejected. Bolt locked back. Next round still in mag. Tried 3 rds. Fired case extracted, not ejected. 2nd round smoked-stacked. 3rd. still in mag. 2nd cartridge somewhat smudgy.
I am using the mag that came with the Oly. Appears to be English. Put new springs and green follower in it. Always worked before. Like an idiot I didn' take any of my G.I. mags with me.
Ok, so I said, the hell with it and went home. BTW, the fired cases appeared normal. I compared them to previous fired cases. Couldn't detect any appreciable difference. Will mike them later. Took the bolt and carrier out when I got home. Ejector seemed ok. Couldn't hardly push it in. Removed the extractor. Spring with blue insert. Had one of Oly's X-rings so I put that in and re-installed the extractor. Checked bolt carrier and it seemed fine. Relubed and put everthing back together.
Will try again later this week with different mag. So...any ideas on what the hell is going on?  
edited. Made up some dummy cartridges to check feeding. Discovered that the bolt catch spring was missing. Where it went I don't know. Has this happened tho anyone?

Quoted: Discovered that the bolt catch spring was missing. Where it went I don't know. Has this happened tho anyone?

Bolt catch spring, or spring AND plunger are missing?  Thats a new one.

Standard  A-2 stock and buffer. And yes the bolt catch spring is missing. The bolt catch just flops around. I made up some dummy rounds and fed them through the rifle while holding the bolt  catch in the open position.  All the rounds fed and ejected normally. In fact they all landed in the same pile. I haven't removed the bolt catch from the rifle yet so I don't know if the detent is still in there. In any case new parts are on the way from Model 1 Sales.
I was shooting the rifle last weekend and I had no problems with it. However, that was with the original 16" bbl. and upper. Go figure.
As soon as the new parts are in I will take the rifle out in give it a try.  I was sighting it in at 50yrds. and it was doing ok on single shot mode. Needed one click down and one click left and she was on the money. First time I ever shot a rifle with an AK brake . Neat. Hardly any recoil to speak of.
Oh well...birthing pains. Next month I want to assemble a new lower  with one of those formerly banned nasty collapsible (sp) stocks on it. Bwah hah hah.
So it still seems to be where the spring launched to and how it got out of there in the first place.