https://youtu.be/bXKps4RRnQ4?t=85 Scroll to about the 1:20 mark
The picture in my head are 9mm, Glock magazines offset 15 degrees from vertical-up, sights 3" above the bore, Owen sub-gun type action, bottom eject, 2.5" stroke to allow a wide range of rounds to be chambered in future offerings. Retain the in-line "stock" of the grease-gun to limit muzzle climb.
Rivet Unistrut inside the PVC housing for guides, laminate the bolt, 450 rounds-per-minute firing rate. After all, we have to make those 10 round magazines last.