I've read of two different stories surrounding the armament fitted to the He 162. One theory (as supported in David Myhra's book) states the first aircraft were fitted with the MK 108, but later ones had to be fitted with the MG 151/20, since the last German factory producing the 30mm weapon had been overrun by the Soviets. An article at
axishistory.com further states the A-2 was "as the A-1" but only with minor differences.
The other theory I've read is the one that states the MK 108, as fitted to the A-1, was too powerful a weapon for the airframe and so it was decided to fit the MG 151/20 and call it the A-2. The A-3 was supposed to be the version that fixed the problems with the MK 108.
So, which theory is correct? Were there MK 108-armed He 162s on hand with JG 1 or not?