CORRECT 22 Hornet dimentions?

F

Fatelvis

New member
Im having trouble finding the correct head measurement, (just above the rim) for the 22 Hornet. I have 3 different manuals, (Speer, Hornady, and Accurate), and they all say about .298"-.299". I called Winchester, and they say it`s .296" MAX. My unfired REM cases are .2925" and .296" after firing, and Im getting head seperations immediately, (brand new brass), and I was wondering if I had an oversized chamber, undersized brass, or exc. headspace. Would a "no-go" guage tell me if I have too much headspace? How does it work? I assume if the action closes on the NG guage, theres too much H.S., right? Just trying to troubleshoot the problem myself. Thanx guys-
 
According to the SAAMI drawings in NRA Handloading, the head diameter of a .22 Hornet cartridge, immediately in front of the rim, is .2989" with a +0, -.0080" tolerance. So Winchester can make them .296" and Remington .2925" and both be within spec.

The .22 Hornet chamber is shown at .3000" just in front of the rim recess, with a +.0020", -0 tolerance.

Headspace for a rimmed round is the thickness of the cartridge rim and the depth of the rim recess in the barrel breech or boltface. For a Hornet that is .065" +0, -.010 on the case rim, .065" minimum, .072" maximum on the gun.

A headspace gauge for a Hornet will only check the rim recess; it will not tell you anything about the rest of the chamber.

You could get some Cerrosafe from Brownell's and make a chamber cast to get actual chamber dimensions off of.
 
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