Chamber Length
Pete; I don't think anything was "standard" in the US before the for runner to SAAMI was established in the 1920's. There is no proof law in the US, and arms and ammunition manufacturers established cartridge dimensions independently or in cooperation.
Several years ago, I bought quite literally, a shopping bag full of old loading components. After reading your post today I remeasured some UMC and USCCo No10 primed paper cases which have never been loaded. Both makes measured 2 7/8 inch overall and 2 13/16 inch from case mouth to the radius at the rim of the brass.
This discussion occurs about three times a year. About five years ago , in response to one of these discussions, I did some dumpster diving and brought home one or two each of each color case discarded at the skeet field. I measured these with a machinist scale and found most were 2 5/8 to 2 11/16 inch long. A few were 2 11/16 to 2 3/4 inch, and I did find some that were uneven that exceeded 2 3/4 inch in length.
We ran a query, several times, in Parker Pages, seeking the source of the theory that long shells provided a better gas seal and better patterns, when fired in a chamber of shorter length. Ed Muderlak found the article, and we printed it about a year ago. A well recog nized arms industry employee found that shooting 3 inch 410 shells in 2 1/2 inch chambers tightend the patterns, although more than 1/2 inch was burned off each case fired. It is reported, but not supported , that major arms makers shortened chambers in the 1930's to incorporate this finding. They apparently discontinued the short chamber policy prior to resumption of sporting arms production following WW 2.
This article was published in the early 1930's. Any Parker with s/n less than 236000 was made prior to the circulation of this idea.
I will close with my favorite Parker chamber length story. My second Parker gun was a trap with BTFE. I bought it from a well known and respected dealer who measured the chokes and chamber lengths in my presence before I purchased it. I later measured the chokes and chamber length by several methods for an article in the old PP. The chambers always measured a little more than 2 3/4 inches. I sold the gun a few years ago. The new owner told me that he had a very reputable gunsmith measure the chambers before he used it. The gunsmith measured the chambers at 2 5/8 and lengthened them.
From these experiences, I have concluded that there is no standard shell length or chamber depth. However, if a shell fails or separates when fired, less damage will be done
to a gun with long chambers.
Best, Austin
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