If you really want to pull the absurdism here, let's talk about how "easy" that really is - It gets pretty hard to double mass while holding velocity constant, just as hard as doubling velocity...

If I can get a 55grn bullet up to 3400fps in a measly little 5.56, what do you have that gets a 110 up to 3400? It's a hell of a lot more powder to get there - a magnum case, typically a long action, eating more than twice as much powder... If I can get a 200grn bullet up to 2600 in a 30-06, what cartridge case do you need to get at 400grn bullet up to 2600? Even a 416 Rigby doesn't get there, eating around twice as much powder... If I want to double velocity, I can start with a 357mag with a 158 at 1250 and swap to a 308win which pushes a 160 to 2500... I can swap from a 300grn 44mag at 1300 to a 375 H&H which pushes a 300 to 2600...I can pick up a 22LR with a 40grn bullet at 1250 and replace it with a 22 Hornet which gets the 40grn bullet up to 2800, or heck, I can stick it into a 223rem case and get a 40grn bullet up to 3750, TRIPLING the velocity for a fixed bullet weight... So we can do either double mass or double velocity, and neither are actually very sensible comparisons...

But the fact remains - momentum equally values mass and velocity, and is not "governed by mass" any more or less than it is "governed" by velocity. Pretty hard to disregard the simplicity of "Mass x velocity"...