I have been using the shake and bake method of powder coating for 3-4 years with no complaint at all. I only cast for rifles and have taken 2 deer so far with my PC'ed bullets. I do a smash test on every batch I process and have never had one fail the test. Accuracy has been outstanding, and I've noticed no issues with barrel fouling but admit I haven't looked too closely at the fouling when cleaning them.
I decided I wanted to get an idea of how my alloy (~10.5 BH) was expanding so I fired a few of them into water. They were both 30 cal, a 170 gr Lee FP (actual wt 177 gr) and a 180 gr RCBS FP (actual wt 189 gr). The picture shows the final wt and the amount of expansion with each. The middle slug passed through the water and hit the bucket wall of my tractor's front end bucket I was using to hold the water containers. Velocities were 1700 fps for the Lee and 1800 fps with the RCBS. I guess I was expecting more expansion but this was it! Penetration with each was about 4 feet.
The picture also shows that practically all the powder coat is gone on the contact surfaces of the bullets. This I was not expecting. Is the powder coat coming off as it goes down the barrel or from the impact with the water and when passing through it? I will take a close look at the barrels I'm using for cast shooting to see what is in the bore besides carbon fouling, which is normally all I notice when cleaning.
I y'all's opinion, it the powder coat protecting the barrel?