So I started and killed a thread regarding a Martini Cadet rechambered long ago to 32-20 and was looking for a solution to correct the bore mismatch to the cartridge. So I thought something in a 35 cal necked down was a good idea. Maybe it is. But its awful expensive and a long time out to have dies produced. I have received much in assistance from Ric in Yakima regarding the possibilities and 32-40 was the final easy answer. I got to looking at the live 32-20 rounds I bought from Black Hills and the Starline brass and RCBS heeled bullet from Buff Arms. In my hands was an assortment of parts. I chamber cast the rifle and about the first 1.5 inch of barrel forward of chamber. Measurements are .315 bore, .320 groove.
After taking measurements, I felt surely there is some better product than moving up to the 32-40. I have 32-20 brass. I have NO 32-20 dies as its very well known that it will serve poorly for the Martini chamber/bore mismatch. My brass will die a quick death for sure.
I downloaded a blank print from PTG. I also came up with some capital for reamers for several projects. I began to contemplate how I could take a 32-20 parent as is, expand neck to 323 for an 8mm bullet (proper for the Martini). The Greener chamber was very short, allowing the 32-20 to clean up the old chamber. Im stuck with certain dimensions. The rim recess is a mess, two diff diameters from the 310 and 32-20 reamers. By setting the barrel back, I can freshen up the throat area and almost purify the chamber as new.
I have drawn a new reamer print, attached. It is an 8mm hybrid. 32-20 parent, expanded to an 8mm proper neck so that traditional GG bullets can fit INSIDE the 32-20 case. There is little margin for error in the throat area. I want to use the RCBS bullet designed for the 32-20/310 cadet. Velocity and pressures will be where i want them with minor changes to the starting 32-20 loads. I will take the mold to school and open the shank from being heeled to being a .3235 shank and Ill leave a .010 lump to form a second grease groove. The bullet will seat deep enough to cover the front grease groove by .005 or so. Like I said its a very, very tight fit for this bullet to be reused for this purpose. Worst case is if failure occurs, Ill order a throater and lengthen the throat another .050 and use a longer 8mm Mauser type plain base bullet thats been hacked on a bit to shorten it.
So the idea is to pull barrel, set back far enough to all but clean up the rim recess. Thats about .060 if I leave a minor remnant of the old recess. I havent calcd the thread pitch so I am not sure how many turns it will set back yet. Hopefully not more than 2. Ill lathe bore the proper .410 rim recess to .065 plus/minus Headspace requirements. Ill index the barrel back to TDC and relieve any interference for extractor, etc, etc. Then ream the chamber with a “weird” reamer.
I set the body to have a .3570 head that extends .2 inch. Zero taper in body for that area. It should add a small increase in capacity (not that it matters). it also gives me a straight walled case head to size. I can bore a die out to .3540, a straight tube to size the case head. Thats pretty cheap to do to an old die. I dont intend to push the cartridge so I dont expect to have significant swelling to reduce. I REALLY DONT WANT TO USE A CUSTOM DIE SET!!
The shoulder of the 32-20 is gone, now just a minor taper to the neck diameter of .338 ID (3415 OD on print for neck expansion). All of .005 of freebore then a 6.5' leade for .070 inch. From measuring the RCBS bullet, I derived the .070 point of rifling contact. The bullet should kiss the lands with significant nose penetration into bore. Worst case is a MODIFY the RCBS mold and add 2 small GG to the shank and use the existing GG as a crimp groove (NOT A BAD IDEA!!) The neck can be resized with a 32 ACP die. Neck expansion with an 8mm mauser die stem. Basically it gets reloaded with a bunch of junk that I can find at the gun show in odds and ends or already have on hand.
So thats the IDEA.
I am certain when I present this to Dave Kiff, he will make suggestions either abruptly or gently.... I am sure I have errors somewhere. Ive never designed a reamer or a wildcat.
Anybody have any input on the drawing? Anyone see major “stupid” stamped on a dimension? Its supposed to be a straightened 32-20 (basically a 32 H&R on steroids).
I am concerned about the cartridge headspacing on the body taper and not the rim after a first firing. But the cartridge will look much like many Sharps BN cartridges but tiny!
I believe if I take it easy on the brass and loadings, I wont need a FL die for a long time. By then, I may have the skills to ream a DIE here at home and do it RIGHT.
For some reason I feel like the case head should be at .3500. Starline brass mics at .345 unfired. From multiple samples and sources. .350 would be less taper in boy to .3415 neck. Darned near straight walled. it will for sure HS on the rim. I can move the neck/body junction back with a 32 ACP die if needed to get fired cartridges to chamber freely after first firing- if needed. At that point I could use a 32-20 sizer that the neck was opened up on. I could do that with a chucking reamer to make the neck area useless. Make a custom body sizer only.
Those are afterthoughts. Ill ask Mr. Kiff for a reamer print of 32-20 std and maybe just modify the existing neck/throat area.
Thanks in advance for your thoughts.
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