I am goint to go out ona limb here and say its not the bullet . If you hit lung / liver short of hitting a rib , this is soft tissue hit . Not many muzzloader rounds shot into a deer size target will expand in soft tissue and they arnt going to upset tissue by velocity.A single lung /liver hit deer will live 6-12 hours.Had you wated 8 hrs and not pushed the buck it would have been where you jumped him off the bed .I am not condeming you .. or the bullets as thats what im currently using .But i spend alot of time tracking deer... and see alot of worst case senario recoverys .