@TheMatrixEquation-balance I'm not asking questions in Space SE anymore - but if you like you can consider both asking "is there now undetonated ordinance on the Moon?" and clicking that little tick box at the bottom which says "answer my own question" and then going ahead and posting this as the answer. I think it's quite a nice piece of space history!

We have both the history and explosives tags

@uhoh - Yes, this is a very interesting question. I had no idea there was a military angle to Apollo missions. I cannot ask questions :) They will suspend my account.

@TheMatrixEquation-balance oic well the application wasn't military - they were using them to create seismic events at a safe distance away from the landing site for the benefit of the ALSEP seismometers they had set up.

But nonetheless a million years in the future alien archaeologists may speculate the first humans that made it to the moon were warriors

I believe the common archaeologist refrain is [see something they don't immediately recognize] "this must be of religious significance"

@TheMatrixEquation-balance I am highly skeptical that simply removing the atmosphere would more than double the muzzle velocity. Sure, it won't slow down, but as you posted before, the escape velocity is >2 km/s. If you don't start faster than that, you ain't leaving the Moon. Low gravity is irrelevant, as that's already factored into the escape velocity.

any amateur ornithologists here?

@fyrepenguin - talking about 2S7 Pion mortar. On Earth, its projectile weighs 50 kg. On the Moon, the same projectile will weigh 5-10 kg. The same amount of gunpowder will achieve a higher muzzle velocity. And if you replace gunpowder with light gas (LOX + LH2), the muzzle velocity might double.

@TheMatrixEquation-balance uh, hwat? The mass doesn’t change, and kg is a measure of mass. And that’s what matters in terms of velocity change from energy input. The apparent weight is different, sure, but I don’t see how that translates to a higher velocity.

@fyrepenguin - "When you move to a heavier bullet in a given cartridge, you also pay a penalty in the muzzle velocity. In other words, you can’t push the heavier bullets as fast as you can the lighter ones". But you are correct. The lack of gravity will play a very minor role in muzzle velocity.

@TheMatrixEquation-balance I’m fairly certain that what you’re quoting is using “heavier” but really means “greater mass” since those are more or less interchangeable on Earth (minor variations in gravity aside). Of course, reducing the “m” in “F=ma” will increase the acceleration for a given amount of force. But just moving the same setup to an area with lower gravity will have no effect. It’s the mass, not the weight, that’s important.

I agree. And I also think that shooting canisters with Deuterium 3 from the Moon to Earth is technically possible (reasonable) even with today's technologies.