I've had the same problem. I usually go with 52 A-Max but the bullet shut down forced me to go the 53grV. I'm going out tomorrow and see if I can tell which one does a better job.
Called the rancher and the dogs are blossoming everywhere. They need my help.
I tried some 50grn Zmax recently as I could not find anything in the vmax. They work just as well. They terminate dogs extremely well. Going back out this weekend again, cant wait for Friday to get here.
Oh do I miss shooting those little guys. I learned a valuable lesson in barrel cool down from those things. Heat bulged a perfectly good barrel. Went from a .222 to a .223 and I gotta tell you, the .222 shot better. I loved that little round.