That super-short pump-action can only hold three cartridges; two in the magazine and one in the chamber (which would leave the weapon cocked and relying in a safety-catch, wouldn't it?) so I too thought about whether a traditional double-barrel would be simpler (and with external hammers safer?). Operating and reloading in heavy gloves might be a consideration too.
Sort of a complicated question, but I'm going with no. Plenty of people in all walks of gun-toting-for-business life carry rifles and shotguns and 1911s with the chamber loaded and the safety on. The thing about external hammers is that if you cock it, and then change your mind about shooting and decide you don't want it cocked anymore, you have to hold the hammer back with your thumb, pull the trigger, and slowly lower the hammer to the decocked (or half-cocked) position. If your thumb slips, well...
The gun community as a whole is
very divided on whether or not this is acceptable behavior. Personally I fall squarely into the camp that does not approve, on the logic that it's a violation of basic safety rules to pull the trigger on a loaded gun without intention to fire it. A single-action semiautomatic firearm should - in my belief - never be decocked on a loaded chamber, since there's generally no way to get a round into the chamber without cocking the gun, and there's no way to decock the gun without pulling the trigger - therefor if the gun is in that state, you violated the rules to get it into that state. Unfortunately it's pretty much unavoidable with revolvers.
Also, whether or not it's really
safe to have the hammer down on a loaded chamber - as in, like, drop-safe - varies a lot from gun to gun; older designs are usually more drop-induced slamfire prone than newer designs. Of course, most newer designs are either double-action (as a refresher: meaning you can pull the trigger to fire the gun even if the hammer is decocked) and have safe-decocking levers to lower the hammer without pulling the trigger - ie without disabling the internal hammer block and firing pin lock safeties - or are double-action only, the firing mechanism never being cocked until you pull the trigger.
Autoloading rifles and pump shotguns are near-universally single-action with the hammers hidden inside the gun, so there's no way to decock them anyway, and you keep the safety on if the chamber is loaded (
condition 1.) Some people aren't comfortable with this and, under the logic that the more work you have to put into readying the gun to fire the safer it is, leave the chamber unloaded (condition 3.) Something you need to take into consideration with this is, if a threat arises, how urgently will you need the gun ready - ie, will you have enough time to cycle the action to chamber a round, or do you only expect to have enough time to take the safety off (or cock the hammer, as it were)?
::deep breaths::As for the double barrel vs. the Serbu snubnose pump, well... I guess I'll do it like this:
Sawed-Off Double BarrelPros:
If "hammerless" (actually has hidden internal hammers,) It can be readied to fire both shots one-handed*
If hammered, can be carried in condition 2 if so desired
If hammered and you cock it, then change your mind and decide to decock it, the action can be opened to move the cartridges away from the firing pins, allowing you to thumb-decock it without worrying about slipping and accidentally firing
Hammered doubles usually still have manual safety levers, so you can still carry in condition 1 if so desired
Hammerless doubles automatically cock when you open the action to reload
Cons:
Hammered doubles are slow and awkward to thumb-cock, and trying to do it one-handed is a bad idea (this I know from experience/practice with my Zhong Zhou** coach gun)
Hammerless doubles are automatically cocked when you open the action to reload, which means it take a lot more force to open the action after firing; doubly so (lawl) with super short barrel like we're talking about here since you don't have as much leverage and gravity on your side (my hammerless 73cm barreled Baikal was
very easy to open)
Opening the action to reload only one barrel takes the other barrel out of the ready-to-fire state, momentarily leaving you at a disadvantage
Most side-by-side doubles require you to pull the fired shells out of the chamber manually when reloading
Hammered doubles are somewhat prone to internal damage and uncontrolled discharge if dropped hammers-first on a hard surface with sufficient force; hammerless guns aren't
Super Shorty PumpPros:
One extra shot over the double if you're willing to carry in condition 1
First shot can be readied to fire one-handed*
Loading cartridges into the magazine doesn't take the chambered round out of ready-to-fire state, so reloading can be interrupted by firing (this is a benefit of pump shotguns in general)
The vertical foregrip makes recoil much easier to control if you're using both hands, compared to the double
Cons:
Subsequent shots require both hands to cycle the action
You have to extend the foregrip before you can cycle the action - the foregrip must be folded up for the gun to fit into the thigh holster
Cannot be carried condition 2 if so desired
Cannot be readied to fire with one hand if carried in condition 3,
and carrying condition 3 doesn't give you the extra shot on the initial draw vs. the double barrel
*Whether or not firing one of these with one hand is actually a good idea I leave as an exercise for the audience.
**What's the Hanzi/translation for Zhong Zhou Machine Works? I've been curious about that.Between the two I think I'd go with the pump action if you're talking about carrying aboard a spacecraft. All things considered I'd rather have a SIG Sauer P226 with a sound suppressor and frangible powdered-metal bullets. Semiauto, much larger magazine capacity, more controllable recoil, and... erm... firing a gun in a tightly enclosed space with metal walls and no sound dampening is bad for your eardrums, especially when you're talking about a 12 gauge shotgun with a 16.5cm barrel. The noise and flash from that is going to
hurt. The muzzle blast/flash would probably constitute a serious fire hazard as well.
Also, firearms realism counseling for authors of fiction is
something I live for. Feel free to ask me questions any time, if you can tolerate my
long-winded thoroughly detailed answers.
