Originally posted by SRT:
M1911 - I'd hazard a guess that your box is pre-war.
The Bridgeport address doesn't necessarily mean that a box of Peters ammunition so marked is post-war. Remington bought Peters in May of 1934, and in 1935, all metallic ammunition production was moved from Kings Mills to Bridgeport.
I have two boxes of Peters large primer, pre-war, .357 magnum ammunition, both #3575, one marked Kings Mills and the other marked Bridgeport. To further add to the confusion, for a period of time, until the stock on hand was used up, metallic ammunition produced in Bridgeport was shipped in Kings Mills boxes.
The Kings Mills address disappeared from the Peters Catalogs in 1940. In June of 1942, metallic cartridge production at Kings Mills resumed, as some .45ACP and mostly .30 Carbine, were produced in support of the war effort.
The Kings Mills Ordinance Plant closed down .30 Carbine production on March 31, 1944, and in July, the plant was closed. A short time later, the Kings Mills plant was acquired by Delco Remy to make parts for landing (Higgins) boats.
Hope I haven't further confused the situation, but it is easy to discern that dating ammunition is not an exact science. Just like we know when it comes to S&Ws, the companies were in business to make money, not to create a road map for collectors. While we have learned to "never say never" in regard to what S&W did, the same holds true for the manufacturers of ammunition.
Hope this helps a little.
Best regards,
SRT
P.S. - The last really nice, collectible, full box of #3575 Peters .357 I saw sold at auction for $660.