Or perhaps I should ask for 22 WMR reamer dimensions.

I bought a 22 magnum barrel off gunbroker and the chamber seems pretty undersized.

Here are the cartridge dimensions:


Measuring the breech end of this barrel, with 2 measurements at 90 degrees to each other, I get a measurement of 0.238 at the 3-9 o'clock position and 0.232 at the 6-12 o'clock position. I find this interesting as if this were just caused by a burr due to repeated dry firing I would think it would be confined to the 6-12 position and the other dimension should be unaffected.

At any rate, my thoughts at this point are instead of trying to ream it is to make a "plug" type of reforming tool to tap into the chamber and see if the metal can be displaced back to the original. My only concern here is if for some bizarre reason the chamber was truly cut undersized and that was ultimately the reason it ended up on GB. For reasons I do not need to go into, I don't think this is the case but it does seem to be the only other scenario I can think of. The seller has offered to take it back as well so I believe he is an honorable guy, I just want to get it fitted since it is here and I am very happy with the price I paid for it.

Anyway, what diameter should I make the chamber reforming plug? Or should I make a couple of them so I don't run the risk of getting one hammered in and stuck there like a nail in a piece of oak?

All thoughts and opinions appreciated!


Mark

This might help.

http://en.wikipedia.org/wiki/....ester_Magnum_Rimfire

A chamber iron is simple. Find a piece of tool steel and slightly taper it forward from about .242. Machine a flat on one side to clear the burr and then give it a high polish. FWIW, I would harden it prior to polishing it. Anyway, apply a little oil and insert the tapered iron into the chamber with the flat side positioned to clear the suspected area. Advance the iron until it lightly seats against the mouth of the chamber and then give it a turn to swage the mouth of the chamber back into shape. Won't need a hammer.

Thanks Malm!

I'll just make the base .242 then and keep it that way for 1/2" or so then put a taper down to .230. Thanks for mentioning about putting a flat in, that makes a lot of sense too.

Because rimfire chambers vary so much in diameter, the irons I use start to taper right off the bat. But it's a very slight taper over a total length of maybe 1/2 inch.

OK. My concern (and I may be mistaken just ask my wife about anything else) is that even after looking at it with some good lighting I do not see a noticeable/sharp burr at the chamber mouth so I am not sure how far the distorted area extends into the chamber, which was why I am planning on having it be the full .242 dimension for 1/2" before tapering it down to .230.

Gotta go do some yardwork, hopefully I can get this done this evening and I'll let you know how it goes.

Are you sure it's not a .22 Winchester Rimfire (22WRF) barrel?

SAAMI 22 WMR Chamber and Cartridge Drawing

SAAMI 22 WRF Chamber and Cartridge Drawing

Well thanks Malm, talk about much ado about nothing! I don't know if it took me longer to write the post than it did to make your "chamber iron", but it sure took a lot less time to use it than it did to write about it!

Anyway, chamber is all swaged up and feeds perfectly, woohoo. Barrel is already locktited into the action and I'll drill it for a pin tomorrow and then hopefully it will be good to go!

Grenadier, it is a 22 WMR. A few years ago I bought a Marlin 57M that had a bubba'd barrel from a marlin 60 that was reamed to 22 mag. Unfortunately it looked like it was reamed with a drill bit and cases all stuck. I found a barrel from a marlin 883 on GB at a really nice price and correctly guessed that it would fit without too much work, which was true except for this chamber issue. I'll post a picture when it is all together and gets some cold blue rubbed on the barrel.