Pintle Mounted Weapons

[Raellus]

I worry that I might be over-crunching the rules here, but my players and I were wondering if pintle mounts are universal (within reason) or exclusively designed for one make/model of weapon.

For these examples, I'm assuming different weapons belonging to the same class (i.e. general purpose machineguns). Could a PKM be mounted on the same pintle used my an M60? Could an M60 be mounted on a pintle used by a FN MAG? Etcetera. It seems like this should be possible, but I'm not sure. If modification is needed, how difficult would said mods be (i.e. required tools, skills, etc.)?

I'm assuming that weapons of different classes probably can't share pintle mounts (e.g. an M60 and a Mk.19 or M2HB). Is this correct?

Thanks.