Home Forums Reloading Bullet Casting Cast bullets in the 300 Blackout

Mark, what you want to do might work out, or not, depends on a lot of variables. If I were inclined to try what you contemplate the very first thing on the agenda would be to slug the bore and determine precisely what your groove/land dims are. Some might suggest you also do a pound cast of the chamber but I'd not do that until it was demonstrated that all else had failed.

If you want to push a large chunk of lead with the cartridge you're going to have fairly high pressure unless you are content with cat sneeze loads. With other objectives at hand the next step would be to insure proper size/fit of the bullet. Some will tell you groove + /002", but I don't think it necessary. Start with .001" over groove and see what happens.

The bullet obviously needs to be gas checked. I suggest you start with an alloy of 50/50 wheelweights and linotype. If you are not up to speed on what pressure does to different alloys, take a look at the following web page.

http://www.lasc.us/CastBulletNotes.htm

Look about 1/3 down the page on the right. My suggestion for the lino/WW alloy goes to the point of having a hard alloy to deal with the 7" twist without quenching or heat treating for additional hardness.

OTOH, left to my own devices I'd set a lower velocity objective, mix a 30:1 lead/tin alloy and hope I could get away with something in the 700-800 fps range. Maybe, maybe not. Would use the bullet below in the lower tier and kill stuff with that one. Is a .309" 185 grain from a Brooks mould. If that didn't work I'd revise the alloy to higher BHN, maybe around 10 or so and try again.



It doesn't take a lot of velocity to kill stuff if it is properly placed, and even on the best of days, the BO does not generate a lot of velocity.