Loading Lee 356-120-TC in 9mm

by AaronB, Thursday, September 19, 2024, 07:04 (26 days ago)

Hi all.

I've just started reloading 9mm parabellum with cast bullets. Never thought I would, but I figured I'm casting and reloading for a bunch of others, so why not?

The Jim Taylor article on reloading 9mm threw the fear of God into me about this cartridge. In particular, the fear of meeting God sooner than I'd planned by over-pressuring the cartridge due to seating depth.

I've recently acquired some Blue Dot, and I like that powder for 9mm because a double-charge won't fit in the case. After consulting a number of reloading manuals I started with 7.0 grains. I'm loading cast bullets out of a Lee mold, the 120-grain truncated cone. I selected that shape because I thought it would feed okay.

Well, it feeds okay, but out of an abundance of caution (re: fear of God, above) I had seated the bullets just deep enough to cover the lube groove. Consequently the bearing surface of the bullet extends into the throat far enough to stick. Pretty tight, too. Test gun is a Smith M&P EZ, about three years old.

I discovered that if I seat the bullets deeper, so just a hair's worth of bearing surface sticks out of the case mouth, the resulting cartridges will feed and cycle just fine, but... (fear of God, above). So I backed the powder charge down to 6.0 grains of Blue Dot.

OAL is 1.060". No particular pressure signs. Can I work up to 7.0 grains without fear of dynamic disassembly?

-AaronB