I'd consider Chuck Hawks a pretty reliable resource.
March 30, 2012, 07:52 PM
So would I.
March 30, 2012, 08:41 PM
Where in that article is the answer provided although it is a nice history lesson?
March 30, 2012, 08:45 PM
I skimmed through the article several times, myself, before seeing it.
March 30, 2012, 10:05 PM
For the actual cartridge itself, see here (http://en.wikipedia.org/wiki/.22_Long_Rifle).
The actual standards document (http://www.saami.org/specifications_and_information/publications/download/208.pdf) (page 13), found at SAAMI, specifies the barrel diameter in their drawings as:
.217 (5.51) Bore Dia
.222 (5.64) Groove Dia
. . . while the bullet diameter is listed as .2255 inches, in a case having a diameter of .226 inches.
SAAMI is the standard, the baseline reference. Manufacturers will vary from this according to their performance requirements.
For example, the 10/22 barrels listed here (http://www.shilen.com/rugerBarrels.html) are specified at .2215" groove diameter. These are match barrels, and will be ever-so-slightly smaller than the factory diameter.
March 30, 2012, 10:57 PM
You will find that some manufacturers spec their 22 handgun barrels at 0.224". Colt started doing this after the 22 WMR came out in 1959 and where you have a dual cylinder revolver it makes sense, but it has caused some concern with Colt folks for regular chambered 22 revolvers such as the Diamondback. I believe the Officers Model Target has always been 0.222"-.223" as I recall. I suspect Ruger does exactly the same thing with their convertable Single Six.
Added: If you are interested in this kind of thing, you need to slug your barrel. But there seems to be no correct answer in terms of barrel diameter.
Also you will find that some 22 rifles will have the chamber manufactured to different tolerances which affects accuracy. This is where the term "match chamber" and so forth comes from.
April 1, 2012, 01:09 AM
For those who (for whatever reason) can't reach the SAAMI document, here's an image grab of page 13: