The base guard has its own base, as you swage them a small button of lead is extruded through a hole in the base guard and expanded to hold the base guard on to the bullet. It is unlikely that the lead will melt off for the small amount of time it is in the barrel. The base guard rotates with the bullet and is as accurate as a bullet with a gas check. I have fired them in both the .45 LC and ACP and they preformed fine.
Donna