Magazine Tubes: Holes along the length to check remaining shells. Holes are also MLok for accessories, but the screw must be flush with inward face of T-nut or it may interfere with shell feed. Print with support unless you really trust your bridging. MLok holes should help with warping as well, but you'll still probably have to sand. Holes for side rails are reinforced with extra perimeters (set slice gap closing radius to 0 in prusaslicer) and can be threaded in directly for light duty, or drilled and HSI'd for heavier stuff. Recommend M3x6mm mounting screws.

Pump: Back lip is bigger and I made the finger tabs taller to increase feed reliability

Future:
Sniper shell Maybe?

Speed Loader + Front piece?

Hip Magazine?

Shell Catcher?