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Creating Brass for the B&M's

For all the B&M series the brass is based off of Remington Ultra brass. One takes any RUM brass and cuts and trims it to 2.240 inches. This gives you first of all, 50 B&M. Just run through the size die and load.

All the basic 50 B&M brass then can go to all the B&M cartridges by just running the basic brass into the various B&M size die. It's just that simple. 475 B&M, 458 B&M, 416 B&M, 375 B&M, and 9.3 B&M.

This is an example of creating a 9.3 B&M, which is the smallest diameter the B&Ms come in.

Basic brass to run through the 9.3 B&M Size die.

With any bottle neck cartridge, one wishes to size the new and unfired case to the point of where it just goes into your rifle with slight resistance. This means the shoulder is bumping in the chamber just ever so slightly and keeps the brass from flowing too far forward when it is fired. This keeps your brass from head separation in the future. Once fire formed, then one can full length size the cases to the point that they go in the chamber with ease.

As you see below the fire formed case has slightly sharper edges on the shoulder than what the formed case has.  

For the Super Short Series the process is identical. The B&M Super Short Series, 50 B&M Super Short, 475 B&M Super Short, and 458 B&M Super Short all use Winchester Short Mag or WSM brass. It too is cut and trimmed, but to 1.640 inches. Then if you have a 50 B&M Super Short, size, load and shoot. The size die for the 475 and 458 B&M Super Short forms the case to their specs, and it is pretty much the same, size, load and shoot as well.

Cutting the parent brass is the biggest chore of creating a B&M case. In the case of the standard B&Ms, one has to take RUM brass, cut and trim to 2.240 inches, then some possible trimming after it's formed. With the Super Shorts, same story, cut and trim WSM brass to 1.640, and some trimming may be required after forming. One can do this on your own easy enough if you have proper equipment. You can even do this the old fashion way with a hacksaw!

I found a little Chop Saw that was made for this cutting operation, very reasonable price and works like a charm. Here you see our Late Friend Sean Russell cutting B&M Brass at the bench during his visit a year before passing.................


Case life is extremely long for all the B&M cartridges. I mean extreme too, I have some that have been fired an estimated 75+ times without showing any problems at all.

Hope this helps some, and please, any problems or issues contact me.


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