Use the same data as any other cast bullet.All the copper plating is for is a buffer to prevent leading in the barrel.Either hard cast,gas checks,or a lot of wax seem to serve the same purpose.Feet per second have a lot of bearing on leading.The hotter you load the more leading you get.I have nothing against copper plated bullets but only use them if I have a firearm that likes them.When loading hot I use gas checks. sam.
Not all copper plated bullets are created equal. I've had great luck with Berry's out of Utah, but had an awful lot of leading from National Bullet copper plated firing essentally the same load in .44 spl. I would like to know if NBC's hard cast bullets are better.
I have loaded 9mm Berry's for a Glock 17, polygonal barrel notwithstanding, and had utterly no signs of leading (just keep muzzle velocity below 1200 fps). I have also loaded 110 gr Berry's in 7.62x25 for my CZ-52, 158 gr in .38 spl, and 100 gr in .380 acp all with no problem.
I dont have an answer except to say the hard cast bullets I have used worked well at moderate speed and if I want more out of them I gascheck.I dont buy cast bullets often because I have done good at casting my own and altho others tell me it isnt necessary today I think mine are better than boughten ones.It took a long time to get a system that works and I would advise someone else to just buy the cast bullets. sam.
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