9mm case length

[silverking]

Can I safely use 9x21mm dies to load for my S&W M&P 9C as well as 9x 19 dies?

 

[GLOOB]

I haven't had the opportunity to try, but I don't see any reason why not. This would be a bit like using .357 dies to load for .38 special (check), or 10mm dies to load for 40SW (check), except you wouldn't have to change the OAL. Just the flaring depth. At least as far as I know.

I've loaded 9x19 with 9x18 brass after accidentally sizing them to 9x19. Worked fine. I just had to adjust the flare die to open them up. Loading 9x19 with 9x21 dies would be analogous.

 

[thorn-]

My Hornady die set for 9mm is marked for 9x19 and 9x21.

thorn

 

[rcmodel]

I don't know.

Two potential problems I see you might have:

* Base and mouth is the same dia, so case taper on the 9x21 is less severe then on the 9mm because it is longer.
Sizing a 9x19 in a 9x21 die may not size it enough to give proper neck tension.

* Maybe the 9x21 seating die will be too long to taper crimp a 9x19?

I guess the only way to find out for sure is try it.

But if you have both die sets already?

Why would you want to have to change the seat & crimp adjustments every time you switch from one caliber to the other?

rc

 

[GLOOB]

* Base and mouth is the same dia, so case taper on the 9x21 is less severe then on the 9mm because it is longer.
Sizing a 9x19 in a 9x21 die may not size it enough to give proper neck tension.

Only if they're steel dies!