Tested my PCC builds today. 9mm using a Stern Defense mag well adapter on standard AR lower. 45acp and 10mm on Spikes Tactical lower.
9mm and 45acp both Delta Team Tactical Colt/Glock style BCGs, and 7.1 oz buffer(9mm) and a 8.1 oz buffer(45acp). Both ran well, and both calibers dropped their empties very close to each other. About 5’ away from me.
9mm is fun. It’s like shooting a 22.
10mms(2 different uppers) were a different story. Both have a 13.4 oz Delta Team Tactical BCG with 10.8 oz buffer. Apparently 24.24 oz combined weight is not enough. Empties were thrown close to 20’ away, and all the cases had a smile and small bulge. I was shooting reloads. Loaded towards the upper end but safe for my 1911.
I have a spare BCG that weighs 14.4 oz, and I have an 11 oz buffer on the way. As soon as it gets here I’ll retest and try for more accuracy testing.

9mm
https://imgur.com/KunYauf

10mm
https://imgur.com/ZfPL3LG

Don't take offence, please, but these guys don't exactly inspire confidence.  Hope your stuff works out.

Most guys don't think 10mm should even exist in a blowback action, so no surprise there.

Well, I would prefer a DI.  But I thought I'd see how well a blowback worked. The DTT BCG is the same as what is sold by many other sites.