Magtech brass, RCBS die, mouth diameter?

[TRX]

Can anyone tell me that the inside diameter of a Magtech brass hull is after it has been sized by an RCBS 12ga die?

Failing that, any other brands of components?

[hubel458]

It has got to be 12ga slug size, about .729" to fit most slugs.
Now with the mouth brass being thinner the mouth od
will be smaller than 12ga specs. Rocky Mtn turned brass
is made thick like plastic case thickness, and od and id
are 12ga specs. Now the RCBS die won't do for the turned
cases. For them I use regular 12ga dies for plastic cases,
an old Hollywood set I found.ED

[TRX]

I should've known you'd be the one to reply, Ed! <grin>

My 12gaFH Maadi-Griffin build has slid maybe a year down the to-do list due to "Real Life(tm)". In the meantime I realized I could at least play with some big-bore stuff by using the 28" Mossberg 500 I have laying around.

What I plan to do is make a bullet mold and load some 2-1/2" cartridges on brass cases. From everything I've read so far, the diameter of factory shells, chambers, and barrels varies quite a bit. I have some Cerrosafe on the way, so I'll soon know my exact chamber and bore sizes.

I'd like to fit the cartridge to the chamber with the usual .003-.006" used for rifle cartridges. Since the chamber is already cut, any adjustments have to be made in the case. I need to know the sized case dimension to know if the RCBS die will be appropriate for my chamber, or if I'm going to have to hone it oversize or just skip it and make one from scratch.

I want the case and the bullet to fit the gun properly, as the first step to see how accurate I can be with a smoothbore.

[gungadoug]

What I have done is to have a die made that sizes the case for about 1/4" to center the boolet, and then give a bit of a roll crimp to hald all together.
Doug