.22LR Sub-Caliber Barrel Insert
 

As mentioned in -

http://forum.lugerforum.com/showthread.php?t=33387

- I decided to make my own .22LR Luger barrel insert and see if a center-fire pistol will fire .22LR cartridges.

I've seen two .22LR Luger barreled extensions [receivers] in the last month, both [apparently] intended to be used with Luger components, not Erma SE08/2 'kit' components.

So I dug out an old .22 barrel stub left over from some long-forgotten short-barrel conversion and turned it down to fit the Luger 9mm chamber and 4" barrel.

Pics below show progress today. :)

I'll thread the insert muzzle and chamber it this weekend or early next week.

It will be single-shot, no magazine feed, no extractor, no ejector. Wooden dowel for poking fired [hopefully!] cases out.

I've read conflicting descriptions of how .22LR cartridges are primed. One source says the primer is a mixture poured [?] into the case, which then hardens, and the powder is added. Another source says the primer is in the form of a thread laid around the base of the case and powder added.

In any event, someone out there seems to think that Lugers will fire .22LR with stock firing pin/breechblocks. There have been two barreled receivers offered for sale. Neither uses the Erma sub-caliber 'kit'. I've never seen a fired .22 case with a center strike, but the bit bucket at the club has about a dozen .22 rim mis-fires on any given day.

I shall see. :)

Rich,
I have a 1900 AE converted to a multiple-fire .22. Pictures can be seen at:

http://forum.lugerforum.com/showthread.php?t=18722 If you would like any other pictures let me know . As the pictures show the original firing pin was adapted to fire rim fire 22's. Bill

Bill - Thanks for the link! It looks way too complicated for me! :)

I followed the link to the "Modification" thread that John Sabato posted, another interesting .22 modification -

http://forum.lugerforum.com/showthread.php?t=18858

I am simply going to find out if these sub-caliber center-fire conversions worked...[pic below]...

Most I've seen place the round off center to achieve a rim strike from a center fire pin.

I'm curious to know if a center strike in a .22lr will ignite it.

I have an Uberti Cattleman in .22lr and it does strike in between the rim and the center of the case. It fires without problems.

A dead center strike will not ignite a .22 rimfire. That is why they can be loaded in tubular magazines, head to tail.

(There is a reason why you will never see a lever action, tubular magazine centerfire caliber with a pointed bullet).

Doug - Can you explain the adapters like the one above? Or the .22 Luger barrels with the bore centered? (The Erma toggle won't fit).

There may be some .22 cartridges that have the primer applied like mentioned above.

There are center-fire rifles that load with tubular magazines. Winchesters come to mind. Blunt tipped bullets are recommended. :p

Doesn't matter. It will or it won't. Some may, some may not. :)

SH, In my accumulation of PO8 parts, I've picked a few different variations of standard PO8 breech blocks and firing pins that have been modified for use with rimfire .22lr. Available cheap, starting @$25 each. TH

Tom - PM sent. :thumbup:

In the meantime, I've faced the breech end of the insert to 9mm case length and reamed the chamber to .22RF. :D

Just for S&G, I loaded a fired case into my barrel insert and 'fired' it with all-Luger components in place. Just to make a firing pin impression. :)

Whoa!!! :eek: That is one big firing pin strike!!! :D

I don't have a needle-point verniers, but my 1/16" square-end verniers shows a .024"+ deep dent!!! That's more than my 9mm Parabellum firing pin strikes!!!

I don't want to do any 'real' test-firing until it's threaded and a nut secures it in the barrel...Just in case... :roflmao:

I also noticed that WLyon's link above uses a spring in the grip for his 22LR Luger, like their bigger brothers. But the spring must be very substantially reduced to handle the lighter load. In the Erma 22LR kits, there are two springs in the toggle and it is disconnected from the grip spring. I find these variations interesting and think WLyon's design is most interesting. As an additional note, the Erma bolt also contains a spring with pin buffer in the back part of the toggle assembly. This acts in a hard recoil when the toggle is completely jacked up, as the toggle assembly does not have a protrusion like a standard toggle.

There was nothing about disconnecting the mainspring ["grip spring"] in the Erma instruction sheet. I don't think that would work either, as the cannon assembly has to move rearward ~1/4" to align the magazine for feeding and ejecting.

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In any event, my sub-caliber insert is finished. Pics below. I had to wait for the 11/32" x 32tpi NEF tap for the insert nut. I made the nut out of brass just for S&G, and *tried* to knurl it at 14lpi but it didn't turn out too good... :grr:

I'll try it out ASAP but as usual I've finished something on a weekend and the club is jumping with shooters. Fall small-bore leagues starting up, center-fire league still going strong, and the occasional cowboy all lining up to shoot. :banghead:

I'll try next week during the day. :rolleyes:

In the 1930s, RWS in Germany made a .22 conversion kit that worked as a centerfire drop-in, not unlike yours. The reason why that one functioned is that RWS developed their own variation of the .22lr round to go with it, called the 'marke N', it was basically a .22lr case with a centerfire primer stuck in the bottom.

What I forgot to mention is that RWS flattened the top part of the insert's chamber so that the standard P08 extractor could catch behind the rim of the .22 round. This meant that by pulling the toggle backwards manually after firing, it would extract the case from the insert. Nice touch :)

I had thought of cutting an extractor notch in my insert (the P-08 extractor seems to drop down far enough) but I was concerned that the extractor hitting the rim when chambering the round might set it off...Making a very expensive zip gun... :rolleyes:

I can't find that article that mentioned 'poured' primer mixture [lead styphnate] but IIRC it didn't mention the manufacturer anyway...I'm thinking that cheap Mexicano ammunition might have the 'poured' mix...

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10 October 2015 Update - I could only get my center-fire insert to work with one brand of .22LR ammunition [RWS IIRC] and then only about 1 in 10 fired, so the project was shelved temporarily. :(

BUT...As mentioned in a thread today -

http://forum.lugerforum.com/showthre...ewpost&t=34872

- There are several Lothar Walther sub-caliber insert kits for sale on eBay. I've looked at pics of them and a cross section and I think I can salvage my home-made insert assembly. :)

Here's what I'm going to be working with -

- My chambered barrel insert, for 9mm cal 100mm barrel, w/nut
- Grade 8, 7/16" bolt [4140 steel]
- Pic of Lothar Walther model 1-70 .22LR adapter

I'll start by turning down the chamber area of the insert to just a short flange.

1 - Cross section of Lothar Walther sub caliber adapter
2 - My barrel insert before modification, with Grade 8 bolt for firing pin adapter
3 - byf pistol used for testing, showing barrel insert in place and just 9mm cartridge in chamber
4 - Modified barrel insert now has .070" flange rather than full chamber step

I decided to use an integral one-piece firing pin, in a 1/16" hole.

5 - Picture of Lothar Walther .22LR adapter cartridge
6 - Turning firing pin holder out of the Grade 8 bolt, extractor groove cut
7 - Drilling & milling the cavity for the center section
8 - Drilling the hole for the .22 firing pin
9 - Pics showing a RCBS small primer decapping pin in .22 firing pin hole[.062" dia]
10 - Milling the .22 firing pin integral with adapter center section
11 - Drilling & tapping the center for a brass insert
12 - Finished unit installed and ready for use

Failure To Launch
 

I took it to the range today...It didn't work. :(

13 - All the parts, different views
14 - From upper left - strike in adapter center section & rim strikes on two cartridges; adapter showing pin protrusion; breechblock showing Luger firing pin protrusion; parts of unit.

The Luger firing pin made a light strike on the adapter center section and the adapter center section/firing pin made light strikes on the .22 rim. Not enough to fire the cartridge.

Next, I will try rounding the adapter firing pin tip and see if I have a stronger Luger firing pin spring. I have a Wolff Spring Pak but I forget if it came with a stronger firing pin spring.

Everything seems to be working correctly, it just doesn't fire. :rolleyes:

You can clearly see the pin depressions on the .22 rims in pic 14.

(The unit itself was originally made for the Tikkakoski 120mm 9mm barrel; a short spacer had to be made for the P08 100mm 9mm barrel.)

The strike looks light and short???

Hi Bill! How ya doin'??? :D

Yep, that's what it is. ;) I turned the cartridges so the strikes would be at ~12:00 o'clock...

I dug out my Luger parts and found the unused Wolff striker springs I stored for a rainy day.

Unfortunately, they are less in diameter and coils than my S/42 striker spring!!! :soapbox:

S/42 - 22 coils, .030" wire dia

Wolff - 21 coils, .028" wire dia

I don't reload and I usually don't fool with primers and such, but IIRC they need an "anvil" to work. Berdan primed cartridges have a teat in the primer pocket, and modern Boxer primers have the anvil built into the primer cap itself, kinda like a double bottom. However, a rimfire cartridge doesn't have a separate anvil, it relies on the pinching of the rim to ignite. If you hit a rimfire case dead center, there's no anvil and no bang. It may go off anyway, but I wouldn't rely on it.

The offset striker should work, but from my own experiments I have found that sharp edges work better than round edges, and you can move it toward the center as long as you still get the pinching effect. A machined, rectangular .030" wide and .040" high protrusion without any extra filing or polishing has worked well for my own builds. Not sure if the length of the protrusion matters as long as it hits the rim.

In short: I believe it could be as simple as filing a bit on the pin, that should make a deeper dent and make it go bang.