CPA Rifle Bullet .32 Miller Short

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My most recent rifle acquisition is going to require a new mould.  What would the experts here suggest we put together for a CPA rifle in .32 Miller Short?

Plain base, breach seated, about 200 grain is my guess. .323 at the base.  Maybe this would be a good spot for a top pour design as the base needs to be near perfect.

Help me design one?

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[SwedeNelsonKeymaster]

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mkastning

Get me some chamber information and will see what we can do
A pound cast would be best, but could get started with a good chamber drawing

Bullet maker, maker
Al Nelson

[barrywgoodwinParticipant]

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Al-The 326407 should be great with a base of .323 for the breech seat chambers.

[Tom MyersParticipant]

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My most recent rifle acquisition is going to require a new mould.  What would the experts here suggest we put together for a CPA rifle in .32 Miller Short?

Plain base, breach seated, about 200 grain is my guess. .323 at the base.  Maybe this would be a good spot for a top pour design as the base needs to be near perfect.

Help me design one?

mkastning,

Last night, I did quite a bit of cyber searching for information on the .32 Miller Short chamber dimensions and could find nary a bit on the chamber.  Found one sketch of a loaded cartridge but that doesn’t help with the chamber length, freebore, and leade dimensions which would be absolutely critical to a functional breech seating design. Like what Al said, an impact impression (pound cast) would tell the story and eliminate a lot of false starts towards the design of a bullet for your particular chamber.

Click on the link below to open the Cast Bullet Design ~ Ultimate helpfile that details one method of producing a useable impact impression.

http://www.tmtpages.com/draw/UltimateHelp/hs40.htm

[craigthompsonParticipant]

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If it were me and I had a new CPA rifle I’d more then likely get one of the already designed molds from someone like Hoch or whomever . And after I got the rifle shooting well with said mold I’d then give consideration to having one cut of my own design .

[michaelkastningParticipant]

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Thanks for the replies while I was away.  I just went out to Puyallup to shoot NOE bullets into the berm at Paul Bunyan! 

Now that I am back, I am going to get going on the CPA.  I have a 32 mould that I can borrow to cast some bullets, lets start there and I will send some out to you Al, with a few that I push into the bore a bit to get an idea of what is going on.

As the moulds that I can find are all base pour, I will be hoping to come up with a nose pour version to keep that base perfect.

Fun project!

Mike

[frankelliottParticipant]

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I missed this discussion, it was on the second page when I joined the forum and didn’t see it.

I have a lot of designs of my own and filed drawings for Paul Jones and Ron Long molds, all for BSed (breech seated) bullets. The designs are for barrels from 25 caliber up to 38 caliber (25, 28/7mm, 30, 32, 33, 35, 38). For these bullets, the twist rate is very important and in match single shots, the twist runs 16 to 11 1/2.

The way to do the discussion is to start them by caliber and twist rate requirement. The old standard twist rate for 32/40 is 16 and the following design is mine for that twist rate. Most Millers are barreled with a 14 twist and many have been rebarreled to faster twist rates, up to the RKS gain twist of 11 1/2. You must know your twist rate, to know what is needed or order for the slowest common rate. Short bullets will work in fast twists but, long bullets WILL NOT work in slow twist rates.

For BSing, the throat is of very little importance and all throats do well with tapered bullets that seal the throat. I could do a tutorial of two different ways to seat the bullet to get a positive seal.

A real selling point for these type bullets is being able to supply base bands varing form .320 – .324 in 32 caliber because the groove diameter can vary from .319 to .323 and even more but, that’s a lot less common. This can of course be done by inturpulation but, would be more expensive if done to order and if Al even wanted to offer it. But, there is a market for it in single shots.

Frank

[chuckvatnsdal]

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WOW!!!
Frankeore-  that boolit is a winner for my CPA 32-40 with a 15″ twist .319 barrel!!!  I need a mold for this boolit!  Nose pour is a great option as well, but need top punch unless we go with pan-lubing and pushthru sizing-
OUTSTANDING design-
THANKS FOR POSTING THIS–

Chuck  358wcf :

[frankelliottParticipant]

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Thank you, Chuck:
Now we just need more people that would like one. I can modify it to be a little better for 15 twist and still be as good for 16 twist by lenghtenig and shortening the base band.

Frank

[barrywgoodwinParticipant]

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Frank-Would there be much of a change for a 14 twist ?  tia  Barry

[frankelliottParticipant]

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While you can use any bullets shorter than a twist will handle, for best results (wind drift) a longer bullet would be better.

For a 14 twist you can use a bullet 1.20″ long, like the one that follows. I can stretch a bullet on the base band to cover a 1″ twist differential but, not 2″ and still have a good balance. I have a Ron Long and Paul Jones that will work in both 15 & 14 twist. They are two different designs but, simular, if that makes any since.

Frank

PS
I also have a drawing for the PJ 235 gr (1.29 long) bullet that works for 12 or quicker twist.

[Author]

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