OK - here's my input...
There are some 7-shot revolvers running around in .38/.357, right? I would also assume that they are full-sized frames with some exotic lightweight metal, no? We all know that recoil is an issue with lightweight frames, and that a heavier bullet will recoil more than a lighter one.
Additional factors - Given that these are to be duty CCW sidearms, going with Titanium or Scandium for a frame is a good idea, as it will help prevent rusting. Cylinders for these are either totally stainless or base metal with stainless inserts, and the barrels are base metal with stainless inserts.
Also, overpenetration is an issue - you don't want to shoot a tango and drop him, but the bullet kept going and will hit the AC skin (I know, not that big a problem mechanically. Think about the psychological effect it will have on the sheeple who don't know anything about airframes) or you managed to hit someone right behind him who just ain't involved.
Also, any armed engagement within the airframe is, BY DEFINITION, short-range/CQB in nature. You just don't need the full range...
Therefore, let me offer this. In 1990, we developed a short-range load for these sorts of things, using a slightly lower powder charge and bullets centreless ground out of Delrin bar stock. That's right - plastic bullets.
Recoil - next to none.
Overpenetration - none.
Terminal energy - Scads
Penetration of soft armour - not a problem.
Range - about 40 yards
Those of you who have read UC will find this idea familiar, but it is a bit older than the book. We came across the idea in 1990, but I think it actually goes back to the CIA/OSS assassination teams, which were disbanded after the Church Committee Hearings (Frank Church should have been strung up by his pubic hair.) The idea was lost, and several military ops units "rediscovered" it recently.
The Delrin bullet idea WORKS. Trust me. It will homogenise any soft tissue it hits, terminal energy transfer is TOTAL, and will not penetrate metal (and has a hard time with sheet.) This makes it a nearly idea carry ammunition for use onboard aircraft, at a significant cost savings conpared with the Glaser Safety Slug - this savings can be applied where it belongs - TRAINING.
FFZ