Machinist with to much time?


January 16, 2013, 11:12 AM
So I was answering a post on the auto pistols board about the .32 ACP and one of those hmm thoughts hit me.

I use a .32ACP shell shrinker in a .308 hunting rifle.

There are a number of rebarrels mausers out there usually from places people speak Spanish or Hebrew.

I just went down to the shop and pulled my little KelTec .32 auto from my pocket and droped the slide in the magazine well of a K-98 Hmmm.

Wouldn't it be a neat project if one of you semi retired machinist came up with sort of a Pedersen device for 7.62 Mauser boys?

Barrel, breech, mainspring and striker firing pin (held back by the rifles sear) in a fake bolt. Ejection almost straight up but a little to the right. Magazine well and release in a block to replace the magazine and floor plate of the K-98.

TO use remove k98 bolt and maga assembly. Insert rifle bolt shaped device and turn to lock, place mag block in rifle magazine port. load loaded mag, work action shoot .32 ACP in semi auto.

Should be not much more trouble than an AR15 .22 LR conversion.........

Running and hidding now.....


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January 16, 2013, 03:05 PM
i had the same bug with 7.62 x 25 in my moisy.

January 17, 2013, 09:54 AM

Two issues with that

#1 7.62x25 is really going to need a looked breech or some sort. Doubt there is room in the mosin receiver for any sort of lock.

#2 as folks trying to use shell shrinkers have reported the .308 pistol bullet used in the Tok cartridge gives poor accuracy in the Mosin.

On the other hand I understand that the Pedersen device was made for the Mosin 91 as well and it s my understanding that the prototypes worked with un modified rifles having no port cut out or modifications to the existing trigger assembly.

Might be an even larger market for Mosin owners for a .32 ACP adaptor than for 7.62 nato 98 users.

On the mausers I wonder if the main spring might not be in the magazine well and worked through a lever like on the Beretta 21 series pistols.


January 17, 2013, 10:21 AM
It's been done:

There are two styles of adapters. The load at the rear type has the advantage of ease of manufacture and ease of reloading. It has the large disadvantage that the bullet has to make a loooong jump before it engages the rifling and encounters any resistance, so much so that the burning curve of the powder is messed up and it never gets a chance to build up the proper pressure. This results in poor velocity, poor accuracy and lots of unburned powder in the insert and barrel. At least that's how my 32 ACP in 30-30 adapter worked out.

The other is load in front and these have the bullet in more or less the normal position. These adapters are more complicated, since they have to have an internal firing pin to transfer the blow from the gun's pin to the primer. They also are slower to load because the adapter has to be disassembled to load the cartridge. They should provide better interior ballistics, but I've never tried one.

January 17, 2013, 09:37 PM

I was not speaking of Shell Shrinkers as something to make up new. Perhaps you should re read the first post.

I am thinking about and trying to get others interested in a Pedersen Device like set up for the 7.62 NATO 98 mausers.

THe Pedersen device was an accessory for the M-1903 MARK I rifle of WWI. This was a standard M1903 that had an ejection port cut in the left side and a modified trigger mechanism both of which allowed the use of the Pedersen device. The Device replaced the normal rifle bolt and allowed semi auto fire from a high capacity magazine of basically a streached .32 ACP cartridge that appearently the French were impressed with as the 7.65 French Long pistol cartridge is a copy of it.

The idea was that a soldier had his "normal" rifle with its five shot magazine n .30-06 for use as a high powered rifle, then before an assault he would remove his bolt and replace it with the Pedersen device and have a very low powered rifle BUT as a 20 shot semi automatic.

Keep in mind that at this time the concept of a Sub Machine Gun was very new, .32ACP pistols were considered just fine for defensive work, this thing fired a slightly heavier bullet at a slightly high velocity and looked great on paper.

They were never used in Combat but several tens of thousands were made and thousands of M1903 Springfield rifles were modified into MARK Is before the idea was scrapped.

There were also prototypes for the SMLE rifle of Great Britain and Prototypes for the Russian M 1891 Mosin Nagant.

Supposedly the Mosin Nagant model did not require a specially modified rifle.

I have used the SHell Shrinker single shots in .32ACP/ .308 and the .22LR/.223 model that has the firing pin piece that is a pain in the behind to keep track of. Long ago ( the late 70's) I handled one of the Marble types that used the front half of the .32ACP case as the neck of the "cartridge" and had the internal firing pin and was impressed.

I did not find either of the Shell Shrinkers particularly inaccurate and seem to recall posting photos of some groups on THR back around my join date. I am considering trying the .22LR/.223 with the Mexican SSS 60 grain .22LR in a 1/7 twist in the near future, perhaps as early as this weekend just for giggles.

I already have been dissapointed in the reliability of firing the SSS in an AR15 .22LR semi auto adaptor, but never fired for groups as I was so aggrivated with the inability to fire more than one shot without having to stop and clear the device.

Again in the late 70's I used the .22LR Cobray made GI conversions in M-16A1and found them to work acceptably and with accuracy on a par with (shot right next to them) a Nylon 66 rifle (not a paragon of accuracy but acceptable for hunting and plinking). However the M16 A1 had a 1/12 barrel twist which was much closer to the twist needed in .22LR barrels than the current crop of ARs.

These experiences taken all together made me wonder about a semi auto conversion device using .32ACP for the 7.62 NATO Mausers


January 18, 2013, 06:16 AM
hey kbob l figured #1 on my own but #2 was news to me

January 18, 2013, 08:25 AM

I have not used the Tok to X54 shell shrinker myself, but that is what other THRers have reported on the one that was available form Sportsman's Guide.

Having forgotten it is a holiday my alarm woke me this AM and I could not get back to sleep and this topic came to the top of the heep in the semi functioning grey stuff.

Here I am talking about a Petersen Device and it occures to me that Petersen invented a hesitation lock that used a fixed barrel in his Remington Auto Pistol design that might be something useful for making a 7.62Tok semi auto adapter for the NATO Mausers atleast.

Hey maybe its time to put the 3D printer crowd to work instead of ya-yahing!

Make a concept model on the 3D printer and then decide how to manufacture it in durable material if the model seems doable.


January 18, 2013, 10:37 AM
If a semi auto system seems to complex, how about something like the old ERMA .22LR K98 adaptor but without the full length barrel as the 7.62 barrel would do fine for a .32 ACP.

Make it use a common .32 magazine and keep it bolt action.

Or even make it 7.62 TOK ( for the NATO rifles) for that matter and use Tok magazines.

As to "will they buy it" take a look at the post about the new $199 Mosin nagant stock one company has invested in.

I also wonder if one could turn something line the shell shrinkers from .22LR barrel blanks and counter bore the rear for the Shell shringer type firing pin adaptor. Make it no longer than need be to fill the chamber. Mark the base some way so you always put it in the same way. No fast swinging shots!

Might be just the thing for the occassional bunny at 20 yards or soda can at 25.


January 18, 2013, 11:17 AM

I was not speaking of Shell Shrinkers as something to make up new. Perhaps you should re read the first post.

I did. I misread it the first time. :o

Mea culpa.

January 18, 2013, 05:08 PM
If someone built a drop in device, turning my Mosin into a semi auto firing pistol caliber high cap, I'd totally get one.

I think the concept is fascinating. I had not heard of anything like this being created.

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