help with 9.3 mold please

[practical_man]

Looking for a little help from the exprienced boolit designers.

I'm trying to create a mold for a CZ550 in 9.3x62. Not a lot of choices out there: NEI, CBE, and ebay.

I made a cerro safe cast of my chamber:
- from end of case neck to the faintest beginning of rifling is 0.375"
- groove diameter is .365
- land diameter is .361
It's a 4 groove barrel with the grooves about twice as wide as the lands.
Twist appears to be 1:14-ish. 9.3x62AL tells me it's 1:13.3, and I believe him (and thank him for trying to help me out through some private messages).

I read a boat load of posts about 9.3 on this site, a few on the CBA site, and looked at pictures of other boolits. I went to the Mountain Molds site and worked with it for hours (way too many hours, but I'm a geo-bachelor right now, so it keeps me out of trouble.)

I came up with a couple of options. The first has a narrow front driving band (.100) and a short nose (.400). The second has a longer driving band (.220) and longer nose (.525, a dimension I borrowed from Glen). Both should fit in my rifle.

I'm looking for feedback on:
(1) will the bullet fit in the rifle describe in this post?
(2) will it be stable?

Thanks for your comments, and thanks to 9.3x62AL and all the other informative posts on this caliber.

-john

[leftiye]

You didn't say what your throat (freebore) diameter was for that 3/8 of an inch. .375" of freebore is enought to have a grease groove or even two in the portion of the boolit outside the case - in my perspective anyway. I think in terms of filling the freebore, not caring about exposed grease grooves (find some other way to keep dirt from adhering), and full diameter to the beginning of the rifling (maybe with the front band bore diameter). Long full diameter body section, and shorter nose portion like you've got resists slumping at higher pressures too. Unless you're after the big meplat, you could stand a little bit longer, more pointed nose. I think in terms of a soft nose (and/or hollow point) to obtain tissue damage while still having a better ballistic coefficient, just my preference (probly not a real popular one either, I know).

[practical_man]

leftiye,

thanks for your comments. Freebore tapers from .374 down to .368.

So if I interprety you right, a thick front band that tapers has some utility. I think your comments would lead me to modify it to remove the crimp grove and design groove spacing so I can crip on one of the driving bands, leaving a lube grooze or two out in front of the neck.

Does that sound about right?

-john

[Blammer]

a thick front band and then perhaps a tapered nose from the band to the beginning of your rifling dia.

This will fit your rifle well and give others a chance to play with seating depth.