.22LR Sub-Caliber Barrel Insert

[sheepherder]

Originally Posted by Vlim

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...

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

[sheepherder]

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.

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.)