Wait did the mig 27 normally come with a 30mm?
Yep, a single GSh-6-30 30mm Gatling gun, a derivative of a naval gun no less.
And fun fact: Soviet and russian Gatling guns are gas-operated, rather than electrical like their american counterparts, and as such tend to be lighter, more compact and easier to maintain, but with the downside that the RoF cannot be controlled like in electrical guns.
But back to the plane, the problem with this cannon, which was very similar to that of the A-10′s Avenger, was that the recoil and vibrations on the airframe of the MiG-27 were so bad, it constantly fractured external fuel tanks, jammed landing gear doors, broke landing lights, shook control panels off, cracked gunsights, and in a couple of occasions, even managed to jettison the cockpit’s canopy! Basically severely limiting its use, where more often than not pilots just didn’t bother and never carried ammo for it, instead opting for more fuel or ordinance.