Long Barrel .22 Conversion

[sheepherder]

Long Barrel .22 Luger project.

This is a commercial Luger receiver [barrel extension] mated to what appears to be a cut-down, threaded, and chambered .22LR rifle barrel. There is a dovetail under the threads (visible in pic #6) and the chamber area was left long, so that a Luger or Erma toggle assembly would not seat fully. There is no extractor cut and no feed ramp in the barrel. There is a blade front sight in a slot cut in the barrel, possibly original [the slot].

The owner also has a complete Erma SE 08/2 conversion 'kit'. Looks like it has never been fired.

I'll be doing the Erma .22 conversion kit adapted to the 7 1/2" custom .22 barreled Luger...

Original Erma parts will not be modified.

[sheepherder]

Steps in pictures

(1), (2), and (3) - Erma 22 SE/2 'Kit'
(4) 7 1/2" .22 barrel on Luger receiver
(4) Removing barrel with barrel vise & receiver wrench
(6) Turning off excess metal at breech end of barrel
(7) Drilling chamber plug 'blank' in 7/8" steel bar
(8) Turning down plug to fit in chamber
(9) Drilling out .22LR chamber for plug
(10) Reaming drilled hole
(11) Facing off blind end of drilled/reamed hole
(12) Milling plug sides to fit in Luger receiver
(13) Plug sides milled flat
(14) Plug snug fit in barrel
(15) Excess metal milled off plug
(16) Plug ready to cut ramp
(17) Muzzle skim cut for concentricity
(18) Plug milled for breechblock clearance
(19) Plug set up to mill ramp
(20) Ramp milled
(21) Cut milled in center of ramp
(22), (23) Slitting saw set up to mill extractor groove
(24) Centering slitting saw with drill bit & spirit level
(25) Finished extractor cut
(26) Reaming .22LR chamber; partially cut
(27) Finished reaming .22LR chamber
(28) Drilling receiver lug & barrel for setscrew
(29) Tapping receiver lug & barrel
(30) Installing setscrew
(31) Side view; finished conversion
(32) Oblique view
(33) Chamber view; toggle locked open

[sheepherder]

The first shot with the modified barrel & chamber plug, the plug backed out about 1/32"...Not good...

I took it apart and re-measured the plug and the reamed-out chamber. The diameter was right on, both OD of plug equal to ID of chamber. It was a tap-in fit. The length of the plug was .001" less than the chamber. The pressure from the chamber was forcing the plug to back out.

So, to fill in that .001", I dripped a couple drops of epoxy onto the end of the plug, and also deepened the setscrew hole a bit more. The next time it was shot, there was no backing out of the chamber plug. The gas leak was sealed.

[sheepherder]

Fired thirty rounds through it this morning. Extractor stayed in place, and even worked correctly most of the time.

Had a lot of slam-fires, stovepipes, failures to eject, failure to c0ck.

Fed single rds from mag very well [surprise], all rds fired first try (when it cocked).

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Had the range all to myself today for about an hour, was able to make some observations...

My slam-fires have mysteriously disappeared; the Erma unit feeds OK, c0cks OK, but has weak ejection with the CCI 'Standard Velocity Target' ammunition. Stovepipes, spent rds caught in breech area, toggle not going back far enough.

Had this happen with my 4" S/42 Luger with complete Erma unit AND the 7 1/2" barrel w/chamber plug using Erma toggle ass'y.

I only shot 20 rds. I need to find something between 'Standard Velocity' (the CCI 'Target') and the 'Hyper-Velocity' (Remington Viper). Logic would have me think that 'High Velocity' should be somewhere in-between but none of the boxes [except CCI] have velocity figures on the box...

While cleaning the various components, I noticed the Erma barrel insert was much tighter on my bronze bore brush and my swab than the 7 1/2" barrel. Much tighter. So I tried various drill bits (solid end) and this is what I noticed -

Driil Bit - Go In???

7 1/2" USA barrel/JC Higgins 22 barrel/Mossberg 22 barrel

5.5mm bit [.2165"] = yes
#3 bit [.2130"] = yes

Erma barrel insert

5.5mm bit [.2165"] = no
#3 bit [.2130"] = no
#4 bit [,2090"] = yes

So the Erma bore is tighter than the USA/SAAMI bores...(Bore only; not the chamber)...

Interesting...

Edit: Oh, yeah - I cut paper 7 times out of the 20!


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I had a few hours last night to examine and try different things. I also spent an hour at the range this afternoon shooting. Here's what I found out -

- The slam fires I had were the result of the sear not engaging the firing pin. I was using my sear from a commercial Luger since I didn't have the owners, and it wasn't holding the Erma firing pin. The Erma firing pin was in the extended position when the breechblock chambered the round, and it fired.

- It was failing to eject because the commercial barrel extension the owner is using is too tight a fit on my commercial receiver. It binds, and doesn't rebound all the way, or go forward into battery all the way.

The Fed rounds feed OK and the primer strikes were all good.

I guess it's true that every Luger part is hand fitted. They're not all interchangeable.

I cleaned everything again, and tried different combinations of frames, sideplates, and sears from my three Lugers on my bench. Right now I have the Erma toggle and the 7 1/2" barrel + extension mounted on my S/42 frame with a commercial sear and a different commercial sideplate assembly. Everything seems to slide nicely without binding and the sear seems to hold the firing pin.

I'll try some more shooting/testing today or Monday. It's possible some of the troubles I've been having could be cured with filing and/or lapping in the parts, but I don't want to modify my parts or the owners. He may have to do some tweaking/fitting. He'll probably have to try the Erma toggle and 7 1/2" barrel/extension on several Lugers to find one everything works OK on.

I'm pretty confident that everything I've done machine-wise is good to go.

***************************************************************

A couple notes on shooting this Erma SE 08/2 conversion kit...

The first time I shot it, I only had Remington 'Viper' 22 LR rounds. When I shot a few rounds, the extractor shot off the breechblock, and landed downrange about 20 feet.. The extractor plunger and plunger spring just fell out on the bench.

When I had shot about 70 rounds of 22 of different values [standard, high, and hyper velocity] through it, it plonked the toggle pin out on the bench. Not a very confidence-inspiring experience.

[Edward Tinker]

i always liked Tinker Toys

[Diver6106]

Note that the toggle pin that came out should have a locking pin that goes down a small hole thru the toggle, near finger grips, into a detent on the left side of the pin. This is like the locking pin on the safety or take down lever. Georg seemed to like this pin method to lock parts in.

[sheepherder]

Originally Posted by Diver6106

Georg seemed to like this pin method to lock parts in.

I must have missed that part of his biography - When did Georg work for ERMA???

[Edward Tinker]

Originally Posted by Diver6106

Note that the toggle pin that came out should have a locking pin that goes down a small hole thru the toggle, near finger grips, into a detent on the left side of the pin. This is like the locking pin on the safety or take down lever. Georg seemed to like this pin method to lock parts in.

Can you provide a picture of what you are saying, because I can't picture it.

[sheepherder]

Originally Posted by Diver6106

Note that the toggle pin that came out should have a locking pin that goes down a small hole thru the toggle, near finger grips, into a detent on the left side of the pin. This is like the locking pin on the safety or take down lever. Georg seemed to like this pin method to lock parts in.

Originally Posted by Edward Tinker

Can you provide a picture of what you are saying, because I can't picture it.

Ed - I couldn't either; your toggle wasn't drilled for an axle pin retaining pin IIRC - and my pic in post #10 above don't show a hole for one either...

...But the Gun Digest parts schematic in the other thread DOES show one...WTF???

[ithacaartist]

Rich, if you need an axle retaining pin, I predict the Erma King will cooperate. Mic the D. and the L. and he can check for one.

[sheepherder]

Originally Posted by ithacaartist

Rich, if you need an axle retaining pin, I predict the Erma King will cooperate. Mic the D. and the L. and he can check for one.

As far as I can remember, this ERMA toggle had no axle retaining pin. My pics don't show any either.

It's not my unit [the ERMA .22 kit], which is why I made no permanent modifications to it. I did not try to 'tune' it, as I only had my own 1937 Mauser Luger to try it on. I no longer have it, but perhaps the forum member who does own it can comment further on this.

[alanint]

CCI Mini Mags provide nice mid-range power between high velocity and hyper velocity loads. They are a standard among suppressed .22 firearm users.

[ithacaartist]

Originally Posted by alanint

CCI Mini Mags provide nice mid-range power between high velocity and hyper velocity loads. They are a standard among suppressed .22 firearm users.

Yup, they work the best in several Erma Lugers of mine--just the thing when a pistol needs a little extra oomph without going crazy about it. They are 1235 fps. Remington Target, 1200 fps. Aguila Super Extra, 1255

The Toggle knobs--the nice, knurled ones on this model kit--look like the toggle knobs from the joints on the KGP series pistols, which do have an axle retaining pin; and I think they are contemporary manufacture, too. My kit is the earlier post-war, which has 'ears", I'll call them, with no knurling and a different shape, like the early kits. So without a retaining pin, how's the axle supposed to stay in? I guess at this point, it would be up to the owner to propose conjecture about this.

[sheepherder]

Originally Posted by ithacaartist

So without a retaining pin, how's the axle supposed to stay in?

I have no idea. If you look at the second pic in post #10 above you can see the axle pin is sticking out already.

[ithacaartist]

Originally Posted by sheepherder

I have no idea. If you look at the second pic in post #10 above you can see the axle pin is sticking out already.

I pulled my 70s Mauser with the SE/08 kit installed today to fiddle with the kit's extractor, which wasn't pulling the empties out of the chamber last time I used it. I was intending to clean out its area and dress the claw, if necessary. (I succeeded only in locking all of the related parts into the breech block somehow, but that's another story.) The corresponding axle in my slightly earlier kit is a press fit. The rear pin is the only one that slides out. It can do this because once installed, it is captivated by the barrel extension, while the other two present open ends--thus the press fit for them. Looks like you'll need a slightly larger pin that will bind enough to stay put.

[rhuff]

Originally Posted by ithacaartist

Looks like you'll need a slightly larger pin that will bind enough to stay put.

Could the pin be knurled for a tighter fit, or is the pin too hard for the process.

[ithacaartist]

Rich, I have a sample of .030 cellulose acetate on the way. I'll forward it to you when it arrives. Here's a quote for a 20"x 50" single sheet of .020 material http://freemansupply.com/quote/myquo...150103020337AM

[sheepherder]

Originally Posted by ithacaartist

Rich, I have a sample of .030 cellulose acetate on the way. I'll forward it to you when it arrives.

Not necessary. I have a sheet of polycarbonate and a sheet of plexiglas on the way. One will work.

Finding the correct glue may be a bother.

[Diver6106]

If you don't have the 'center pin key', I guess you'll have to peen the two ends of the axle so it doesn't come out, but is still flat enough for the toggle to close. Or other options, such as modifying the pin to a screw fit or other mod. As a side note, the Stoner LMG had faulty locking pins with a screw design holding the grip to the frame in the earlier versions, and they fell out and killed some SEALs. After that it was modified with a snap in pin that precluded it from falling out. Locking pins are a simple concept, but faulty ones can ruin your day.

[sheepherder]

Ed's toggle isn't drilled for either axle pin retaining pin, but the Gun Digest schematic clearly shows them [#15 & #18]. It also shows the axle pins having grooves that the retaining pins fit into. Ed's pin (the one that fell out) was not grooved.

Cost cutting measure???