We go through a good amount of 10mm at my job. I have recently become interested in 10mm as I've bought a G20 Gen4.
I remember when 10mm Auto was being developed in the 80s. One of the reported "downsides" was its use of the Large Primer. Lot of folks disliked that because on that small casehead, the Large Primer occupies a large portion of the real estate and makes it more-likely that the ejector will strike the primer while you're unloading a live chamber. This results in an out-of-battery detonation. Every reloading manual/website that I can find on the 10mm still refers to it being loaded with Large Pistol Primers.
Imagine my surprise when I found that a majority of the brass I was seeing had Small Primer pockets. I am finding no reference to that change in SAAMI paperwork. I can see why they did it (streamlining the logistics chain), but the change eliminates my option for loading 10mm on my Dillon 1050s. Trying to cram an LP into an SP pocket is a sure-fire way to have a Primer Magazine explosion. I've lit one Large Primer like that whilst loading 45 ACP, but luckily didn't light the tube....
I remember when 10mm Auto was being developed in the 80s. One of the reported "downsides" was its use of the Large Primer. Lot of folks disliked that because on that small casehead, the Large Primer occupies a large portion of the real estate and makes it more-likely that the ejector will strike the primer while you're unloading a live chamber. This results in an out-of-battery detonation. Every reloading manual/website that I can find on the 10mm still refers to it being loaded with Large Pistol Primers.
Imagine my surprise when I found that a majority of the brass I was seeing had Small Primer pockets. I am finding no reference to that change in SAAMI paperwork. I can see why they did it (streamlining the logistics chain), but the change eliminates my option for loading 10mm on my Dillon 1050s. Trying to cram an LP into an SP pocket is a sure-fire way to have a Primer Magazine explosion. I've lit one Large Primer like that whilst loading 45 ACP, but luckily didn't light the tube....