It is probably a Russian 12.7mm machinegun (might actually be a Russian designed machinegun manufactured under license in Iran) and Iranian 12.7mm ammunition. Very compatible.
I wouldn’t get too excited about the coaxial machinegun and the ammunition. Sounds like a case of practical logistics. US M2HB .50 caliber ammunition might be harder for the Shia militia to get than the 12.7mm ammunition. So, dismount the M2, build an adaptor plate to mount the 12.7mm machinegun in the coaxial cradle (or just swap out the cradles entirely) and get back to work.
I would be concerned about the other technologies in the tank(ballistic computer, laser, turbine engine, etc.) but those horses are long since out of the barn. Happened the moment the Iraqis allowed the Shia militias (along with their Iranian advisors) access to the vehicles. There are probably a couple of the tanks already in Tehran being gone over by Iranian engineers.
From what I understand, the FMS version of these tanks does not have the US “green metal” armor package so that bit of technology may still be safe.
But with the Obama administration, who knows?
Russian 12.7mm machinegun and Iranian 12.7mm ammunition.
Yeah, makes sense. Just put on the Abrams mount.
Iran can try and reverse engineer an M1A1 it doesn’t mean they could build a replica that’s worth a damn.
They’d have to get Russian help just to get some sort of bastardized composite armor up and running.