I have been toying with the idea of a 9mm upper for my registered Group Industries lower for a while now. I have lurked, scanned, and read the FAQ's here and other places and thought I had made a decision. Then I talked to people and now I am back where I started.
I had decided on an Oly upper and mag-block because of the ability to use unaltered Sten magazines and trigger slap issues. I found a new Oly upper (16" bbl, complete), buffer, bolt carrier, bolt, block, 1 mag package for $650.
I also found a new RRA upper with bolt and carrier for $540. Everything else is extra.
I was told that the Oly using unaltered mags has functioning problems because the mags can fit loose. The goal is, of course is to have a smooth running gun with as little tweeking as possible.
Anyone with solid experience? Opinion? Ideas? Suggestions?