CORRECT 22 Hornet dimentions?

Fatelvis · December 9, 2002, 08:27 PM

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-

Jim Watson · December 9, 2002, 09:09 PM

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.

grinch1958 · December 11, 2002, 01:39 PM

Try this link I found.

http://homepages.ihug.com.au/~bkhornet/22hornet.htm

December 9, 2002, 08:27 PM	#1
Fatelvis Senior Member Join Date: June 10, 2001 Location: Lockport, IL Posts: 490	CORRECT 22 Hornet dimentions? 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-

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December 9, 2002, 09:09 PM	#2
Jim Watson Senior Member Join Date: October 25, 2001 Location: Alabama Posts: 18,535	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.

December 11, 2002, 01:39 PM	#3
grinch1958 Junior Member Join Date: August 24, 2002 Location: DFW TX Posts: 7	Try this link I found. http://homepages.ihug.com.au/~bkhornet/22hornet.htm