Primer size question.

[Grendel]

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.

TIA

[SI VIS PACEM PARRABELLUM]

Yes there are 10mm cases manufactured today that use small pistol primers. I don't load 10mm but the same issue exists for .45acp in that they now use both size primers. When sorting brass now I sort for primer size so I can prime each size separately. I've encountered no issues using standard spp in .45acp.
Depending on the powder you are using and the load charge a magnum COULD yield better results but either one will make the round go bang. This is where working the ladder comes into play. You may find loads on the ladder that perform better with mag vs standard or even no change at all. Handloading is fun and the experimentation just adds to it.

[cracker57]

40 and 45 both are using SPP and LPP, makes sorting brass a pain in the (rhymes with brass). although when you can only find primers in one size and not the other you can still load for these calibers.
 Good luck.

[sparkyv]

For range fodder, it won't matter much.

If they need SPP, should I use just standard or Magnum, if it even matters.

TIA

[Grendel]

okay, thanks all. Thought I was going nuts.