I now shoot my .45-70 with 400gr and 500gr powder coated boolits. I don’t gas check and they work fine. At first I thought it was because of the large diameter and relatively low velocity. Then I got to thinking, what is the main purpose of a gas check?
As I have come to understand, the gas check is just that. It checks or stops the gases from cutting past the base of the boolit and melting lead, causing it to be deposed on the barrel. It’s not there to completely seal the boolit. The obturation of the boolit does that.
PC coatings can withstand a great amount of heat. Trying to melt culs down proves that. Then can’t the PC stand the gas cutting gases and protect the boolit and barrel? So why do we use GCs with powder coating where a plain base PCed would do the same thing?