After a lot of head scratching, some years ago now, I figured out that some manufactures produce 7.65 Browning cases with significantly different extractor groove geometry than others, and that this has a strong effect on reliability of many pistols chambered for this cartridge.
I first encountered this when a friend’s Nazi proofed Walther PPK demonstrated an intolerance for every US load except Winchester’s, and any/all european-manufactured loads.
Later, I found the same bias in other european pistols, including the Hungarian PA-63, Spanish “Ruby,” and FN/Browning’s FN 1900.
What happens, to the best of my ability to determine, is that most US manufactured .32 ACP cases fail to fully nest their semi-rimmed “over-diameter” fraction of their rims within the extractor groove of the underlying case. As a consequence, a tiny gap is formed between the web areas of the straight walled bodies. This gap creates an additive error, which after a certain number of cartridges, will create a failure to adequately support the top cartridge in the magazine while it is being fed, causing feed jams.
There are a couple of solutions I’ve found. One is to short-load the magazine to fire only the number of rounds of a particular US-type the weapon can reliably cycle. The better solution is to use cartridges with the larger-pattern extractor grooves.
My questions to you gentlemen are:
Do we have two standards here? Is there in fact a US standard case and a european standard case?
Did Winchester always make their cases like the european cases, or are they in fact simply now using european manufactured cases?
What US manufacturers, particularly prior to 1990, made .32 ACP cases with these larger extractor grooves?
Are there guns which actually work better with the scant extractor grooves seen commonly on US-made cases?
Thank-you for your assistance. I’ve got a thorny forensics question that this pertains to.