Forming 9.3 from 8mm

I have some 8x57 brass and need 9.3x57. I have: New Hornaday 9.3x57 dies with the elliptical expander, CFL Case Forming Lubricant (Contains Amine Phosphate compounds), Hollywood Sr. press. In the past, to make 10.5x47R from 9x47R I fire formed the brass. This means several trips to the range, a 45min. drive one way. It worked well and I lost none of the brass. Still using it, in fact. I am using CH4D (Dave's) dies, with a standard expander, and was afraid of crushing the case.

Now, with the Hornaday expander, is it worth trying to do the whole thing on the press? No, I don't have a 9mm expander. My 9's are 9Mak's. I wouldn't anneal until the cases are expanded, I don't think. My brass is supposed to be once fired (yeah, I know).

I can always fire form them, I know how. I'm just curious if anyone else has used the Hornaday expander for sizing up?

Wayne,

Since the 8X57 is a reasonably affordable parent case, I would try one or two to see if it works.

As long as the bottom of the elliptical expander will fit easily into the case mouth, I don't really see any problems doing it this way. The cases might come out a little bit short, might not.

I have not used a Hornady die to expand case necks, but I have done .30-06 to .35 Whelen with RCBS's tapered expander plug with no problems.

Robert

Have you considered using 9,3x62 brass as the parent case? Only needs run thru the FL sizing die and trimmed about .200".

Idaho, I hadn't looked for it. I'm guessing it will be more expensive and less available than the 8x57 but frankly didn't think of it.

Thanks, Robert. That was my thinking but I thought I'd pick other's brains as well.

FWIW, I needed 9.5 X 56.7 M-S cases some time back and found it easiest to form them from 35 Whelen. The longer Whelen cases allowed for a slightly longer trim length after forming with standard reloading dies with less neck expansion. The first firing would form the cases precisely to the 56.7 case length by slightly reducing case OAL.

Using 8 X 57 cases gave thinner necks requiring larger expansion in the F/L die to meet neck diameter requirements, and shorter case OAL with less case life. 30-06 cases were the next best for forming via the F/L die.
The 9.5 M-S is also known as the 375-400 Rimless Nitro Express of the British.

BvT

If you don't mind trimming just use once fireed 30-06 brass. There is a lot of it around and if you lose a few pieces no big deal just buy a few more.
You can even use military brass so there is no caliber designation that is incorrect.

I do form 8x57 into 9.3 in one go in my Hornady tools.. no problem.

Yes, do the thing on the press.
Lube the inside of the 8mm neck lightly
(I use an RCBS nylon case neck brush with lube on the bristles.)
Set the die for full length sizing with expander installed.
Also lightly lube the outside of the case.

Center the case neck on the expanding punch and pull the handle.
Full length size the case, should be EASY
Now retract the ram, DONE.

8x57 (.323) to 9.3x57 (.366) is a SNAP

Mike

I do the same thing by taking 30-06 up to 35 Whelen.
EASY!!!!!!!!!!!!!!!

Thanks, guys, you've convinced me. EDG, since I already have an 8x63 and a 30-06 and military brass I want to avoid that combination. Even though the length should be a give away.

I have a RCBS Form/trim to make 8mm from 06 brass. I just leave it a little long and my Hornaday 9.3 x57 works well. A small amount of lube works. To much will crush the shoulder.