The 9's are blow back. Some are doing DI uppers that have good reviews. I'll stick to the blowback system.
Whose bbl you using same for lower?. I have an early oly 9 upper (uses sten mags) runs like a top. I am interested in doing a dedicated 9 lower that uses glock mags. make it a sbr for the spouse. Supposedly the Quarter Circle 10 lowers can use the oly with ejector removed. If not i'll build one using the JP BCG, since it's already cut for the ejector of a Glock spec'd lower.

