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Chambering a rimfire barrel

gappmast

Cast Iron
Joined
May 13, 2007
Location
California
Gentelmen

I have done a fair number of center fire chambers in the past, but this will be my first rimfire. I thought it would be easier and faster to ask for advice rather than figure it our on my own. I'm looking for information on cutting the extractor groves. How close do you get the grove to the chamber and what size key way cutter works best? Any other information would be more than welcome.

Thanks
 
What action are you barreling? Extractor grooves vary as to width and also radius of the extractors. Generally it works best to copy the factory width and radius and how close the grooves are cut to the chamber.
 
I grind woodruff cutters a couple thousandths over the thickness of the extractor and hold the barrel in the dividing head. I cut within .005 inch of the chamber. (approximately) Then I flip the dividing head over and cut the other side.
 
It's a new copy of a 40X and I don't have any old parts to copy. I'm thinking the diameter of the cutter has to be important to get the angle of the groves right. What diameter cutter do you recommend?
 
Extractors usally have ends radiused, match diameter of cutter to them as close a possible. Width can be wider but will be a place of gunk to build up in if too wide. Skip Ebert recommended on the Turbo for the grooves to lift the extractors off the rim of the case when bolt was closed for best accuracy. I also leave a .005" flat from groove to chamber edge. Have done several 40X's but do not remember which cutter diameter I used, will try to look tomorrow and see.
 
I use 1/2 inch radius most of the time. In a perfect world the extractors should not touch the barrel or at least, should not apply enough pressure to move the bolt around. In a perfect world the cartridge case and/or the bolt body should align the bolt. Most 22s are pretty far out on tolerances and bolt to receiver fit so a lot of time its just not possible. At any rate you want to stay away from having the extractors pushing the bolt nose around.

Gunsmith Rod Henrickson RF Extractor.jpg
 








 
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