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corerftech
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My 32 cal x 357 mag fixed chamber and case attempt
Sep 7th, 2017 at 12:33pm
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Ive discussed here on the forum a few times my desire to forge a 32 cal in a 38 special, 357 mag, 357 max fixed. I have contemplated and then tried to define a set of generic tools that could produce a case and chamber to use as a platform. I know its been done already in several different ways but when I call the reamer companies, they reply "gee we just don't know, draw something up and we will charge you money for it". Tried to find a reamer on file remotely close, nope. C&H makes dies but for what chamber. I asked and got a nice but unhelpful reply.

So forge ahead. All so that I could repurpose a number of 8x58 rollers with their own barrels have then stubbed internally. I like the BUNNY GUN firearm. The 32 S&W being almost perfect. Problem is if bigger nads are desired the firearms that most 32 S&W (formerly Long Colts) are based on are tapped out with 1.8 gr of BE and a 9x grain bullet.
I need .323, not .312!!!

I shoot 38, 357M, 357Max. Ive pondered the 8 Nambu neck on a 38/357/max case. I LIKE FIXED AMMO, I don't yet breach load and I hunt small game. Fixed and small game with trivial cartridges work. Money IS AN OBJECT. I must do things CHEAP especially when they are an experiment.

Here is what I have at hand to screw with:
I have a GRIP of 8mm dies (32-20, 8 man, 8x57, 32-40, 8.15, 32 ACP, etc)
I have a lathe and mill
I have a custom neck/throat from PTG which cuts a .338 neck and a short throat 1.5 degree, little freebore for use with converting the Cadet in 32-20 to use .323 bullets.
I have a grip of 8mm take off barrels to destroy.

Here is whats has been completed:

Finally when 8 nambu arrived, I was able to dig through my MOVING MESS and make a 357 mag with 8 nambu neck/shoulder. That produced a undersized neck for seating as expected. I seated a 323470 unsized in WW dropping at .3235 max after using an 8x57 expander ball. That made a huge .342 plus neck. So I made a special rcbs outside neck mandrel for the new un-expanded nambu form neck and turned to a wall thickness of .009. 

I must admit that I chambered a barrel just prior to the neck turning using a boring bar (.376 body for a length of about 1 inch with no rim recess) on a take off barrel. I then used my neck/throater to open the neck to .338 and ran it very deep so that I had a very long neck, simply to allow imperfect and arbitrary neck length on test cases) I milled the camber open about 45% for inspection and fitment.

Continued on next post.
« Last Edit: Sep 7th, 2017 at 1:26pm by corerftech »  
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corerftech
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Re: My 32 cal x 357 mag fixed chamber and case attempt
Reply #1 - Sep 7th, 2017 at 1:10pm
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I then was able to determine when neck diameter was acceptable given the bullet used for neck expansion and was able to view the shoulder contour, also confirming WHAT was sticking if something was tight.

I have a perfect (dimensioned perfect, roughly cut) chamber at this point meaning its well under a SAAMI spec in the body for runout/oversize from target. The neck has about .0015 to expand. 
My boring bar was a 6mm tool HSS bar, hand ground as a single point tool. A pin gauge was used to examine the body contour and it was a very uniform fit. But the shoulder is formed by the very small radius on the end of the cutter and that is still very sharp and square.

I have attached a pictures. Please look at the shoulder (bottom pic, lower shoulder view) and let me know what I may be able to do for a real chamber to break the edge to some degree that won't cause a separation under pressure or make the case stick. 

EDIT: There is a RADIUS on the shoulder now that I see under magnification of picture.

Ive been thinking overnight about making some form of a .376 pin shaped cutter that has a sharp edge milled into the face at 15 degrees or maybe even 30. Im not a great tool maker and moving has me cursing every time I take a step as I work now in a mess of boxes waiting for Sept 29th to get here.

These questions are all asked so that I can cut ONE chamber to use as the basis for pressure testing. I own an RSI system pressure system. Id like to work up a broad data sheet on both 38 special and 357 mag cases (two diff guns). The MAX option need not be expressed as brass cost is high and not sundry, the cartridge soon becomes more potent than needed as well. Its an attempt to produce a high load density, short case operating at or under 25kpsi for use in the 8mm Swedish action and 8mm standard barrel (self sleeved for use as a new virgin barrel). If the test subject doesn't either kill me or prove completely worthless, Ill then set some standard dimensions and have a reamer produced that will allow NO NECK TURNING (compensating for forming of brass so that EFFORT is no longer needed for fitment). For now I make the chamber with whats at hand and modify brass to fit.

If you all think that the crappy shoulder won't be a problem, Ill do my best to make a radius on a real chamber and chamber one asap.

Appreciate the patience with the long read and your wisdom.

Mike
« Last Edit: Sep 7th, 2017 at 1:30pm by corerftech »  
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marlinguy
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Re: My 32 cal x 357 mag fixed chamber and case attempt
Reply #2 - Sep 7th, 2017 at 2:21pm
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I'm just thinking out loud here, but have you considered short chambering using a .32-40 reamer? It might be that the .357 Magnum case could be used by running it into a shortened .32-40 die to make a .32 caliber straight taper that's shorter? Something the .357 Maximum could be shortened to, and longer than .357 magnum, but shorter than .32-40.

Since the .357 Max is a .379" diameter, one could determine at what point the .32-40 is also .379", and stop the reamer there. A quick measurement of a .32-40 case tells me it might be around 1.5" long, so closer to a .357 magnum. But that would still be a nifty little .32 based on the .357 magnum cartridge. And cutting off an old .32-40 sizing die would make a cheap way to reload for it.
Just a thought.
  
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ledball
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Re: My 32 cal x 357 mag fixed chamber and case attempt
Reply #3 - Sep 7th, 2017 at 2:39pm
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Pin reamers are fairly inexpensive, there's a size "l forget" that will cut a chamber close to what you want.  Ledball
  
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craigd
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Re: My 32 cal x 357 mag fixed chamber and case attempt
Reply #4 - Sep 7th, 2017 at 3:10pm
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Just another thought. Maybe, with the machining that you're doing anyway, you could make your own reamer. Who knows, maybe you can tweak your design before you cut some flutes and save the cost of a custom reamer.
  
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corerftech
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Re: My 32 cal x 357 mag fixed chamber and case attempt
Reply #5 - Sep 7th, 2017 at 3:23pm
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I see that Vall! In my head at least.

A lee die may have its head on the chopping block.

Still interested in hearing some feedback on current shoulder situation.

You reminded me my first inclination was to use 223/556 reamer ala Miller Long and give it a neck but then my mid just exploded both in stupidity and amazement.

And now that Im looking at it, why the heck didn't I contemplate a 223 based solution all along. I was STUCK on a rimmed cartridge! I have 223/556 rougher and finisher.
It would even be easier to calculate on quick load starting loads and powders. A 32 blackout!!!! the neck will almost be gone, nearly a straight wall, could be loaded with black powder, pistol powder and the slowest of rifle stick powder....... and the brass is darn near free. Dies are in my hand.....

OMG----- I just thought this through as I typed. Mind Blown.

I ordered a lee 32-40 die set for $32.00 delivered.
Going to chop a set up.
Ill shorten to the point that the taper is at .375.
I can run a 32-40 reamer in 1.035
I need to remeasure but I think I land perfect to suit 38 special. Including neck length.
I have a set fo 32-40 but need a backup to kill.

Great suggestion Vall. Im on it.

If it works, it would be easy to have a 32-40 reamer cut that the body stops growing at .375 and long enough to suit a 357 max case. One reamer to cut all three options.
« Last Edit: Sep 7th, 2017 at 5:27pm by corerftech »  
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marlinguy
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Re: My 32 cal x 357 mag fixed chamber and case attempt
Reply #6 - Sep 7th, 2017 at 6:31pm
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Can't wait to hear how this works out! Sounds like a very efficient little .32 cartridge!
  
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corerftech
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Re: My 32 cal x 357 mag fixed chamber and case attempt
Reply #7 - Sep 7th, 2017 at 6:56pm
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Was dimensioning the system and the nominal groove for 32-40 is .321 and the neck only .339

The bullet needed, like the NOE 325-130 which is .002 fatter than my current bullet under test and way undersized for accuracy on most 8mm rollers..... will obviously expand the neck appropriately.

The concern is that I have to neck turn any case until something is standardized and a proper reamer ground to accommodate the neck wall thickness.

Not a problem for the one-off. But that is the new concern. About to go out and modify die and report back on its behavior on a 38 special and 357 mag.

The NOE 325-130 actually satisfies better, the Cadet 32-20/8mm conversion better as well (accuracy standpoint)
  
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Re: My 32 cal x 357 mag fixed chamber and case attempt
Reply #8 - Sep 7th, 2017 at 11:11pm
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Why not just grind a much more pronounced radius/angle on the point of your boring bar to soften the shoulder and do it like you did it? Looks good to me. 

If you're concerned about the shoulder/neck junction rather than the shoulder/body junction, just turn a rod to chamber diameter with a taper at the end, and put a dab of grit on the taper section to lap the sharp edge off the shoulder/neck junction.
  
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corerftech
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Re: My 32 cal x 357 mag fixed chamber and case attempt
Reply #9 - Sep 8th, 2017 at 1:00am
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Marlene, Thats a great idea. I thought about lapping it and didn't think it would work well enough.  I agree, just make a bigger radius on cutter, easiest.

Was able to chamber the same 8mm takeoff mauser barrel and will have pics in the AM. The reamer cuts the perfect 38 special based chamber. Used PTG fixed pilot 32-40 SAAMI

Ended up that in order for me to have the superb tight chamber Im looking for you must use 38 special and trim neck length a tad. That offers FULL support at the case head on once fired 38 special. Head is dead nuts .3745 and the chamber is a press fit at the head. 357 mag is not a compatible case due to 32-40 taper.
The combo of neck to case head isn't perfect. I think I trimmed the 38 special post sizing to about 1.140, it had grown a bit. Leaves about .010 for neck clearance. A very very very small fill out around the neck/body and again friction fit the case head.

I had to neck turn the case to get a .323 bullet to fit and have at least .001 of neck expansion. There might not be .001, it may be a bit less. Too tight to be shooting w/o another tiny relief to the case neck.  This all means that a .325 bullet isn't going to go w/o serious neck relief or opening the neck portion of the chamber. The 323 bullet is completely unsupported (this barrel, this reamer), that sucks.

I believe I will go ahead and chamber a roller I have ready with it. Ill plan on shooting .323 bullets and tediously neck turn about 30 cases. If that goes well and I see some velocities where they should be and the cases for as they should and extract and blah blah..... I'll have a reamer cut for a .325 bullet/neck, no throat (so I can throat after the fact to fit the intended bullet), front half of a 32-40 and case head at .375 with NO rim cutter so I can advance the reamer forward deep enough to use longer cases like 357 mag and 357 max. The one reamer and one throater recipe that will fit three cartridges.

Man Vall, this was the hot ticket. I have a correct reamer that I can use to pseudo the cartridge and a die set to produce live ammo. I will still do a rifle with the bottle neck 357 though.

Dies used:
32-40 (cut down very short), forming
8x57, expansion
32-20, the tiniest of flare to the case mouth to start bullet.
32-20, LAME SEATER with about a half inch of runout!!
  
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Re: My 32 cal x 357 mag fixed chamber and case attempt
Reply #10 - Sep 8th, 2017 at 10:39am
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I'll be following this closely!  I have gone the route of .30 whisper on a .357 max case with entertaining results.  I have a source of 8x57 WWII German machine gun barrels with cut rifling and a supply of those Simpsons rollers to play with.  Sounds like an opportunity to make another roller for ground squirrels!
  
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corerftech
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Re: My 32 cal x 357 mag fixed chamber and case attempt
Reply #11 - Sep 8th, 2017 at 11:44am
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Fishoot........ exactly!!
The intent though is to reuse the swede barrel. Of course that's your choice 
The beauty of the swede barrel is the fore stock is fit already, the underlug doesn't move so the stock screw stays put, the channel gets wider with respect to the barrel contour (brown colored bedding??) and possibly the rear sight goes right back on.

Not sure what is less work and less work is the key. Rework wood on mauser barrel, new sights, thread the barrel and make fresh fit cuts..... or reline in essence the old barrel with its own guts.

Pictures of the final 38 special with Lyman 323470 seated, 32-40 front end.

Ive also attached a barrel completed and ready to fit extractor and chamber.
Theres a seam there somewhere.
« Last Edit: Sep 8th, 2017 at 12:10pm by corerftech »  
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marlinguy
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Re: My 32 cal x 357 mag fixed chamber and case attempt
Reply #12 - Sep 8th, 2017 at 12:09pm
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What a great looking little cartridge! Should be fun shooter too! Kinda reminds me of the .32 Long or .32 Extra Long, but tapered from the larger rim.
  
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corerftech
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Re: My 32 cal x 357 mag fixed chamber and case attempt
Reply #13 - Sep 8th, 2017 at 6:23pm
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Slugged the candidate bore with a fattish bullet, fully engraved land and groove.
Also used a mold block lathe plate I built as a final exam in machine finally.
Originally adapted to a clausing with 1 1/2-8tpi nose, expedited it to a four jaw, dialed it in and then used the four jaw fixture which has deadblow hammer adjustable jaws to dial in the Rcbs cadet 310-120 I received from Art Ruggerio 6 mo ago. The base band has some taper to it, I used a 6mm HSS rod ground as a tool, I should have done like the front band, run in to length, set depth of cut, run back out to dimension. I touched off on the edge of the mold face and there was some deflection of the tool until the cutter bit solidly. Next boring tool will have a better edge geometry for the purpose. Wont matter after the Lyman die is done with it.

Been meaning to open the shank up to .323 for a 32/20x8mm cadet and this was the push to get it done.

I was able to open first band and make a base band and a grease groove. It needed to be larger than .325 on WW alloy so I could size and lube in Lyman H&I. 
Hoping as it ages it doesn't grow another .001!
First time cutting a mold, been wanting to experiment for a while now.
Seems to have played out well.

Surprisingly prior concentricity was out .0005 and that was corrected.
Bullets fall from it. The sprue falls off the plate, single greatest casting experience Ive had in 15 years. The 323470 I was using, eBay junk, what a debacle. I may have to attempt a repair!
This is the intended bullet for the 38sp/8mm goofiness I'm executing here.
Received this old ideal mold today as well, 321427 Gc.
136 Gr. Not sure if it fits the bill at all, maybe it casts fat. Oh well.
« Last Edit: Sep 8th, 2017 at 8:40pm by corerftech »  
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Re: My 32 cal x 357 mag fixed chamber and case attempt
Reply #14 - Sep 9th, 2017 at 1:49am
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Same trick works with an 8.15 x 46R case/reamer. Call it the 8.15 x 40R on the max case.
  
Willis Gregory, aka singleshot
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