Problems with 9mm side charger upper

So the big disappointment today was the operation on my new 9mm AR.

It has a PSA Colt SMG lower and a side charging upper from Matrix.

What I suspect is the ejection port is timed to work with Glock style lowers. Using the Colt style lower it throws the brass in such a way that it fails to exit the chamber and fouls the next round.

I tried it with two different bolts, one ran better than the other (which is to say worked 70% of the time instead of jamming every round)

I have a Glock lower and will test the theory some day soon but in the mean time I thought I would post to see if anyone else had a similar issue or any ideas.

Couple pics of the brass and the side charger upper next to a PSA slab side factory 9mm upper

IMG_0399.JPG IMG_0400.JPG
 
I would agree it's a timing issue. Strange I always thought the lower differences were purely magazine style.
 
I was disappointed, I really like the combo of the side charger and Colt style lower.

I have a Glock lower gun with a slab side upper that runs great and I also have a 80% lower with a mag block which runs the SMG mags that runs great.

I'll get it worked though but it was discouraging to have something I was really excited about flop so spectacularly :(
 

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