Pretty good proof here (look at the hardpoint amount)
There is double hardpoints on the wings but for AAMs those are single, but between the engine intakes it can take 2 double AAM hard points, so 6 R-77s on wings, 2 R-77s under intakes, and 4 R-77 between intake. (Note these missiles shown in image are R-27, which is much larger than R-77, so R-27 cannot use double hardpoint.
It has more drag due to technically having more energy, the 77-1 should have less overall drag compared to the base one at the same speeds due to the streamlined nose and improved fins. now unless they model the variable drag properly I do agree the 77-1 will not beat a 120 against a maneuvering target at long range, and even with the proper variable drag modeled it will still fall slightly short to it as at those ranges the sustainer won’t be burning and it will eventually drop below Mach and the drag will increase substantially
the r77-1 is not better than the aim120a/b in a real match, the reason the su30sm gets 12 r77-1s is to counteract that the r77-1 is a bit less dogshit than the r77