One of the primary causes of a Garandicon slam fire is failure to inspect the firing pin leg and the safety notch in the belly band that runs under the rear of the bolt when in battery, most often it is not a soft or high primer. Years ago I had a Garand come into the shop that would at random slam fire. I installed a new firing pin as the original had a very badly worn leg. The safety notch was also worn. I sent a paper photo to Clint Fowler for his opinion to see if it need to be re-welded and the receiver then re-tempered. He seconded my opinion that the notch was still serviceable. The new firing pin solved the problem. Special primers are not needed just inspect your firing pin leg and keep a new spare handy.