Why not just go with blank firing guns?
Shell ejecting, heavier recoil, some muzzle flash, and will sound closer to the real things...

Or is there not blank firing replicas of actual guns? I don't know these things much

Needs an Armourer/ Weapons Master.
Outside of permits and legality, WM knows things that props guys don't.

Had a buddy do a musical some years back that got hit in the face with powder/ wad because nobody taught the lead how to cheat viewing angles by not actually aiming a hangun at his face, for example.

Edit: Also, guns are really, REALLY loud. Stage blanks are still *really* loud. Will spike and clip on most sound rigs unless the sound guy really knows what he's doing/ has budget for the right gear/ outdoors and set up correctly. Not worth it unless you are Michael Mann working with a Michael Mann size budget.