Apart from casting bullets (which I have started doing), I also got the idea to use pistol brass as jackets for 404J bullets. The idea as such is not new, and certainly not mine. From what I understand, 22LR brass can easily be made into .224 bullets, and that this is somewhat popular.
Anyway I looked into it, and found that 40 S&W or 10 mm Auto cases would be the best candidates, as the dimensions are really close to the needed .422"-.423". However, lacking any mechanical skills or tooling, it took until I made contact with a fellow having both, and also a healthy interest in reloading and the will to figure things out and make them work. Also, due to corona quarantine, he had some time to spare. Thus my ideas started materializing.
He built a the tools needed for core seating and nose forming and sizing, and sent me a small test batch to try out. They ended up at around a fairly light 320gr, as the 40S&W case is a bit shortish. Here seen next to a 400gr A-Frame, and a 450gr Woodleigh.
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Using the GRT internal ballistics simulator (a bit like QuickLoad), I figured out two different loads. 74.5 gr Norma 202 and 78 gr Norma 203B (same as RL-15) were chosen. As the bullets are filled with pure, soft lead the seater die made its mark on them.
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Nevertheless, the results were quite satisfactory for a first test; the N203B load produced a group of about 37mm (~1.5"), and the N202 load about twice that. Chronographed velocity was 763 m/s and 756 m/s, respectively (2500 and 2480 fps). All shots from a bench, 100m (110 yd), and scope set at 6x.
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Now awaiting the next batch to be delivered. The first batch was only 10 or 11 bullets, this should be closer to 90. Should be able to actually test a few more different loads. But in all honesty, I am more than happy with 35-40 mm with homemade bullets.
/cmk