Long Barrel .22 Conversion

[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.

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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.