I hav been casting for about 40 years using alox, various kinds of lube, soft and hi temp. Have tried the spray on paint. I do not use harbor freight powder having tried it and found it lacking. Powder is obtained from powder by the pound, it's of higher quality and coats better. Cheap broiler used to cook with. basically the method is described in a previous post. it adds about 2/thousandths to the diameter. results? i have pushed 250grain out of a 375winchester rifle to about 1850fps, no issues at all, no leading, clean barrel.
in a handgun using a 310grain lee mould for 44caliber, i pushed that bullet at over 1200fps with a thompson contender. barrel looked like it hadn't had anything fired in it. the bullet went through seven gallon water fillled milk jugs bounced off a piece of plywood and was recovered. Looked like i could use the same bullet again. Your speed is mainly limited in the process by how big your oven is. Mind will do about 70 at a time at 15minutes. so, 4x70 i am doing 280 an hour. would be faster if i had a bigger oven. I live in phx, and it's hot. bullets store well, non messy like alox or lube in the heat. I can adjust somewhat the diameter coming out of the mold by the alloy, and with the powder coating get right to the diameter i want meaning no sizing. an example is a .452 bullet dropped from the mold, powder coated, it goest to .454 which is what i was after. You can use gas checks if wanted and i have powder coated with those on the bullet, but i just dont see any leading without them. I have done this with 358bullets up to 45/70 bullets. a pound of that good powder goes a long way, you don't need much if you shake them properly. i use as a container for that one of those plastic containers luncheon meat comes in. I dont want to go back to lube. i have a bright red for some 41magnum bullets i cast, a loaded round looks like my wifes lipstick container. sometimes i load red, white, and blue alternating just to be patriotic. typically use different colors for different weights. i do preheat, and i do check the temp other than what the toaster is saying. as another poster said, you can check how well you did by taking a powder coated bullet and hitting is flat with a hammer. done right it isn't gonna peel. this can be very exciting technology as in deep hollow points powder coated. they just really work well