Primer size question

December 29, 2023, 04:39 PM

For the first time, I'm reloading some 10mm using assorted brass. it has all been tumbled, deprimed, reamed, sized, and checked for OAL.

I'm using large pistol primers but so far out of 55 cases, I've had about 12 that won't accept the LPP. Could some of these (I've checked, they are all marked 10mm) cases be for small primers?

I've not tried any yet since I thought 10mm required LPP. If they need SPP, should I use just standard or Magnum, if it even matters.

December 29, 2023, 05:14 PM

ugeesta

Looks like 10mm’s do come in SPP as well.

Cartridges with SPP for sale

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December 31, 2023, 12:44 AM

Bisleyblackhawk

quote:
Originally posted by ugeesta:
Looks like 10mm’s do come in SPP as well.

Cartridges with SPP for sale

This seems to be spreading from .45ACP to other calibers…about 25% of .45ACP brass I pick up as range scrap (especially after our County Sheriff’s Department uses our range for qualifying) our city police are still banned for giving away the gate combination to our private range…why the changes in primer sizes…it’s gotta be that ammunition manufacturers are preparing for upcoming changes to availability

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December 31, 2023, 10:10 AM

Pyker

Thanks all. I thought I'd got a bad batch of primers or something.

December 31, 2023, 11:22 AM

Chris Orndorff

The difference between large and small is, or should be, visually apparent. Might some of your cases be nickled Speer? Speer crimps their primers in Gold Dot loadings and the primer pocket must be chamfered to accept the correct primer. At least that has been my experience reloading for 45ACP.

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January 16, 2024, 11:07 AM

cee_Kamp

Drawing from the SAAMI website.
If you keep two appropriately sized twist drill bits on your reloading bench, you can use the shank (the part of the drill bit that goes in the drill chuck) as a pin gauge.
One for small, the other for large. Verify shank diameter with a micrometer or accurate caliper.

Primer_Primer Pocket Dimensions by cee_Kamp 32ACP, on Flickr

January 25, 2024, 09:46 AM

flesheatingvirus

quote:
Originally posted by Chris Orndorff:
The difference between large and small is, or should be, visually apparent. Might some of your cases be nickled Speer? Speer crimps their primers in Gold Dot loadings and the primer pocket must be chamfered to accept the correct primer. At least that has been my experience reloading for 45ACP.

First thing I thought of. As has been said, it should be obvious if they are large or small primer pockets.

Is that it or did you just have seating issues?

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