I'm using Wolf 223rem 55gr fmj ammo in my dissapator, with no problems but it won't cycle through my 20 inch (not enough energy to cycle)...  
I'm thinking that the slightly heavier 62 grain may have enough blowback to work in both...   Any opinions??
 The 16 in. dissapator has had about 2000 rounds of various ammo through it and the 20 inch about 250 rounds...
 Another thought was that the buffer action spring may be a bit stiffer in the newer rifle...  Thoughts?

That shouldn't be happening , check and see if your gas rings on the rear end of your bolt are all 60 degrees out of alignment. If they are not gas may be escaping into the reciever and not carrying the bolt backward.