by Hoot » Fri Jul 07, 2017 10:18 pm
Unfortunately, I could not find any bullets in QuickLoad that would serve as a reference for ones made of brass. This we can assume: Brass is going to be harder to squeeze down to the bore dimensions than copper but once there, they are slipperier than copper and the Bushmaster factory uppers use a chromed bore which is in all likelihood adds to the slipperiness of the environment. My gut feeling is that they are probably going to jump to the leade and stand up for a while longer than jacketed copper, then scoot down the bore faster, so while a slipperier environment lends to a faster burning powder, that hardness doesn't. You're going to have to pick your way through the weeds in the dark, if Lehigh doesn't do some testing for you. Given the opposing properties, I would load as slow a powder as I believe the caliber tolerates like AA1680 and see what charge yields what velocity minus pressure signs. Once you have a benchmark, it will be easier to jog in powders with a faster burn rate. Not a good prospect for bullets that cost so much as it'll take a lot of them working through to a solution. They may well be the cat's pajamas one you find what they like, but there are other good choices for bullets that have established track records. I'll ruminate on the 454 Casull results when I get some time. We may be able to correlate that given there are plenty of load options in QuickLoad for them. IE, we can model a 5 inch pistol load using a 250gr copper bullet and see how it compares to what they show for the brass ones. The problem is that the 450b is a horse of a different color than the 454 Casull in many ways and a 20" rifle barrel will obviously be able to take advantage of slower powders than a 5 inch pistol.
I'm busier than a one armed paper hanger right now, but I'll try to find the time to do some modeling.
Hoot
In Theory, there is no difference between theory and practice. In Practice, there is.