Anyone have any advice for setting up a 9mm upper on a standard lower? Looking at magwell blocks for Glock mags…curious what I should run for BCG and charging handle.

Just bought an unknown upper cheap, has a 16” 1:10 twist. Will most likely chop and put on a pistol lower, potentially with folder.

Main questions are:

- What’s an ideal barrel length for a PCC in 9mm? - What’s the best magwell to retain LRBHO with Glock mags?

Trying to keep lower swappable to 5.56, so maybe folder is not the route. I guess I’d need the magwell to be easily removed, as well.

Thoughts?