If it was done, would it be better to do it by weapon or by ammo? What do you think?
Definitely by ammo. This would allow for some GREAT alterations that would be a real blast... Such as #4 Buck vs. 00.
#4 Buck 2 3/4" shell generally has 27 pellets @.24 caliber.
00 Buck 2 3/4" shell generally has 9 pellets @.33 caliber.
Also, the spread is terrible on shotguns in X-com. Like ABSOLUTELY USELESS at anything other than point blank and also makes enemies armed with shotguns a joke. Right now I don't even sweat a cultist with a 12 gauge at anything more than about 10 tiles. Because they can't hit shit, or they wing someone with 1 pellet which doesn't really hurt/ kill an Agent.
I mean seriously.... the rule of thumb is a about an inch of spread in a yard; which is being REALLY generous. It's more like half that in most cases. So even, if we were to reduce the spread to something we as gamers can find usable and that tips its hat to shotgun behavior of video games I'd be stoked.
I've also looked at the calculation on how accuracy for a shotgun works and as far as I can tell the first "pellet" and last pellet share the same accuracy...But, I could be wrong....Someone correct me?
Also, spread as defined by weapon would be sweet, because that would mean that even though we have 2 guns that mutual ammo, they have different characteristics when fired through said gun. So, like the the spread on the super short break action vs the 30" barrel goose-gun would be completely different despite using the same ammo.
I would vote for ammo - the current implementation does have its uses since the 'first' projectile is most likely to hit. I use it for frangible-type long range weapons. Then you could have your proposed buckshot / birdshot balance, and finally slugs. It would also allow for backwards compatibility.
Please no birdshot...oh please no.... Unless we could have breaching charges that REALLY fucked up doors; I'd be down for that.