Maybe close to the route I take. If I so choose to take that leap. Been checking published data on plated of the same weight and starting is usually 20 -22 grain. So 19 grain should put me in that 10% reduction safe zone with that powder at 55 grain.
Going to try and find published data on lead in a bolt action to compare. Only problem I can see with your method, would be me, getting the right combo of fit, gas check, and alloy to keep from mashing the bullet into a ball and lining the barrel with lead. Think I could make up for some of the variables with neck only sizing, and PC though.
19 Grain. Would that not put you at like 2500 fps?? Kinda fast for lead isn't it?
Do not know, just asking, as I am very new at this casting thing and have a lot to learn.
I ran these tests before I got a chrono, so all I have is math-based guesses for velocity on that load, but yeah I think 2500 is in the ballpark. It's faster than you would traditionally hear for lead projectile velocities, but as long as it's hitting what I'm pointing at, I wouldn't say it's too fast
I know people on this forum are shooting closer to 2800 FPS with cast .223 without issue (and with better accuracy than I have ever recorded to date).
If you powder coat and size to at least .225" or so, I don't think you'll have leading no matter how fast you push it, particularly with a gas check. Some of the higher end loads I tested were straight up jacketed load velocity with IMR 4895, in the range of 3k FPS, and although accuracy was garbage (indicating that pressures were totally overwhelming the bullet's structure), my barrel was still squeaky clean at the end. In my experience, you have to really be putting forth a lot of effort to lead a barrel once powder coat and gas checks are in the equation.
Whenever I get around to testing lead .223 in my AR again, the starting point for me will be a good 93/3/4 Lead/Tin/Antimony mix or somewhere in that zip code, probably air cooled to start and heat treated if I feel like that might tighten up my groups later. Ramshot TAC or H335, maybe IMR 4895 if those two don't get me where I want to go.
I already shoot practical pistol competitions with cast lead in my 9mm, and am currently working up a load with M193 jacketed 55s for my AR because I'll be shooting 2 gun come August. The dream would be to replace the .223 for 2 gun with cast. I expect if I could get good accuracy in the range of 2800 FPS, I could probably get away with shots out to 300-400 yards okay.