yz,
That's just about it, exactly...
The extractor needs to be tuned to hold the case against the breech. Get it to do that, and half the battle's over!
Problem is, with .380 ammo there's a whole BUNCH of variation on rim thickness, much more than .45 ACP...
So, I've basically adjusted my P-3ATs to fire my favorite defensive rounds, and get perfect performance with them. If it were to malfunction with other brands, I wouldn't care...
A .45 is MUCH easier to tune for, and more forgiving.
Flyer