One minor addition should be considered. Gas operated actions would have some difficulties in a vacuum. Indeed, some may well explode, as there is no atmospheric pressure to balance the high pressure in the gas cylinder.
It is my understanding that the gas pressure inside a firing weapon is much higher than atmospheric 14.7 psia. If not, the bullet wouldn’t be able to leave the gun. 14.7 psia is a fairly small percentage of the overall interior pressure. Ergo, it wouldn’t make all that much difference.
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Even a gas operated gun wouldn’t have any problem, they take some gas from inside of the barrel to operate the guns and the parts are more than strong enough to hold the pressure inside side the gun even in a vacuum.
That was a rather interesting column. Like a lot of people, I assumed that the oxygen in the air was important. Of course, if it was, the small tightly packed and sealed powder wouldn’t get enough oxygen to go off. It must depend upon the oxygen in the powder!
Apparently I’m not the only one confused. In an episode of Firefly, Jayne has to fire his gun in outer space. According to WIkipedia, the writers had checked with gun experts, but were incorrectly told by them that a gun can’t fire in the vacuum of space.
Actually, that wiki page on the Firefly episode brings up a valid point. There are other effects of being in space besides just the pressure differential.
One big effect is that sometimes objects of the same metal will fuse together due to the lack of gas molecules between the metal molecules. This can be a big detriment to mechanisms, which require moving parts to operate. However, this can be mitigated by loose fit parts, surface finishes, and lubrication.
Lubrication itself can have difficulties. Regular grease is subject to its own pressure effects, and can outgas, or even freeze. Typically, astronaut tools replace grease with either space-rated liquid lubes or more often dry-film lubricants. These are materials that are solid but have low friction coefficients.
A third problem is thermal effects. If the gun sits in shade or sun for some length of time, the temp can get excessively hot (+400 deg F) or cold (-250 deg F). This can lead to problems with mechanisms where dissimilar metals have different thermal expansion coefficients, so grow or shrink at different rates, causing jams.
So there may be legitimate issues with using a standard firearm in space. However, operation of the round and combustion of the powder are not.
I don’t think this would be a problem. You are talking 14 psi difference between sea level and space, trivial relative to the pressures used within the gun.
Consider, in an aircraft gun you do not need to compensate for the altitude of operation.
These are the things I always tell myself every time I watch Our Mrs Reynolds.