Chamber dimensions

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Last Post 21 January 2021

Standard Member

unclealtkp posted this 12 November 2020

I am new to this forum and fairly new to cast bullets in black powder cartridge rifles. I am having a custom reamer made up for a 32-40 that I am building for my granddaughter and was wondering what the best dimensions would be? What I am thinking is neck .002 over loaded cartridge size, throat .0005 over bullet diameter with a leade angle of 1 1/2 degrees. Does anyone have thoughts on this? Any advice I can get will be much appreciated.

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CBA Member

RicinYakima posted this 13 November 2020

You have the basics. Check on the ASSRA forum, as they have lots of opinions.

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Standard Member

unclealtkp posted this 13 November 2020

Thanks I will do that.

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rjmelehan posted this 21 January 2021

I am new to this forum and fairly new to cast bullets in black powder cartridge rifles. I am having a custom reamer made up for a 32-40 that I am building for my granddaughter and was wondering what the best dimensions would be? What I am thinking is neck .002 over loaded cartridge size, throat .0005 over bullet diameter with a leade angle of 1 1/2 degrees. Does anyone have thoughts on this? Any advice I can get will be much appreciated.

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32-40, great cartridge...

So unless you are into turning the necks on your brass, I would buy as much brass as you think you will ever need.

Same lot number etc. I found brass thickness go from 12 thousands to 15 thousands from different manufacturers.

I would do this before I had a reamer made.

I have about 200 pieces of new 32-40 brass from Winchester I use to make my 35-40 Maynard cartridges.

UN FIRED they are 2.125" long, brass thickness at neck is .0125-.013

I had a couple of custom reamers made for a 38-55 and a 35-40 Maynard.

I specified a chamber dimension where I planned to neck trim to 11/1000 with a specific bullet diameter cast at 20/1 (,001 over groove) and as you said a neck .002 over loaded cartridge size. I also have a leade angle of 1 1/2 degrees.

In both of these rifles I have a free bore of .20

My bullet design, has a front driving band that fits exactly in the free bore.

When I designed this bullet to fit (nose rides on the lands) (driving bands at or .001 over groove)

I anticipated that this bullet is be used over Black Powder.

If you are going faster than BP velocities,( using smokeless powder) then I would use a harder cast bullet.

(maybe .002 over groove)

Apologies if this info is 'old news'