It's an RRA upper with ramped bolt, Hahn mag block, Colt magazines, 9x19 buffer.  Cases eject weakly and sometimes don't eject at all so the bolt tries to strip a new round from the magazine but the empty case is still floating around and gets jammed between bolt and chamber.  Is there a weaker buffer spring I could use?

I've never had to deal with that problem, but heres a guy who has.

I copied this from the Hydraulic buffer thread.

It seems he was having the same problem as you, but the light spring didn't cure the problem.



"I was running an MGI w/ the weak spring that comes with the AAC buffer. I was having problems with the bolt not going back far enough for bolt catch to be engaged on the last round. It was short stroking.
I'm also running a ~5" barrel with a suppressor.
I figured I wasn't getting enough back pressure and the MGI was too heavy for it to move the bolt back far enough. I was suffering from stovepipes.
I switched to my Hydraulic Enidine buffer w/ the same weak AAC spring and it is running perfectly now. Suppressed and un-suppressed."

Quoted: It's an RRA upper with ramped bolt, Hahn mag block, Colt magazines, 9x19 buffer.  Cases eject weakly and sometimes don't eject at all so the bolt tries to strip a new round from the magazine but the empty case is still floating around and gets jammed between bolt and chamber.  Is there a weaker buffer spring I could use?

It not short stroking, as the bolt is indeed coming back at least far enough to get behind the case in the mag and strip it off the mag...

Unload the firearm, look in the eject port, slowly draw the bolt rearward, and verify the ejector appears from the bolt face high and tight to the minimal cut out provided, so as to get maximum contact with the case to knock it clear of the upper --- refer to the pic..... mine actually could use bend up slightly, but mine works fine, see how close the side of the ejector rides the bolt -




Also make sure your extracted case is not tapping the lip on the mag, if the mag sit too high.