.40 versus 10mm Primers

[Tex929rr]

Why does .40 use a small primer and 10mm a large? I’ve googled and can’t find anything explaining the reason. I’ve been shooting mostly .45 for years and I’m out of large primers but have about 1500 small. So I guess I’ll be reloading a bunch of 9 and .40 for a while. Maybe even some .380. Since the .40 case dimensions are the same (except for length) as 10mm I don’t understand the difference.

 

[HKSig]

More powder capacity on the 10mm?

 

[Texas45]

Same reason 45ACP uses large (some being made with small now)
I just dont know what the reason is.
I am however sure it is a good one.


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[Dawico]

Why does .40 use a small primer and 10mm a large? I’ve googled and can’t find anything explaining the reason. I’ve been shooting mostly .45 for years and I’m out of large primers but have about 1500 small. So I guess I’ll be reloading a bunch of 9 and .40 for a while. Maybe even some .380. Since the .40 case dimensions are the same (except for length) as 10mm I don’t understand the difference.

When the 40 S&W was developed they went with small primers to reduce the chance of an out of spec ejector hitting a primer on a live round.

That didn't make sense to me but it's what I read at the time.

I guess that wasn't a concern when the 10mm was developed. It may have something to do with the bigger powder charges as well.

Keep in mind this was all 30 years ago and technology has advanced quite a bit.

On a side note Glock had 40 S&W firearms on the market before Smith and Wesson did. S&W developed theirs first but had to recall them all so Glock beat them.

 

[Tex929rr]

I didn’t know about the 45 cases with small primers, but that may be a temporary solution to my problem. I see quite a few for sale at reasonable prices. I’ve loaded all my 45 cases and had a lot more than I realized anyway. I won a Glock 23 in .40 at a raffle so I might be shooting more .40 than I used to.

Given powder advances I wonder how much shorter all these cases could be if designed today. When I first started reloading almost 40 years ago I was shocked how little room the powder took up in a .38 special case. I reloaded some 44 specials yesterday (the last of my large primers) and the powder is way down there in the case.

 

[Texas45]

I didn’t know about the 45 cases with small primers, but that may be a temporary solution to my problem. I see quite a few for sale at reasonable prices. I’ve loaded all my 45 cases and had a lot more than I realized anyway. I won a Glock 23 in .40 at a raffle so I might be shooting more .40 than I used to.

Given power advances I wonder how much shorter all these cases could be if designed today. When I first started reloading almost 40 years ago I was shocked how little room the powder took up in a .38 special case. I reloaded some 44 specials yesterday (the last of my large primers) and the powder is way down there in the case.

New Blazer seems to be small primer in 45acp.


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[Charley]

The original Cooper designed 10mm Super, for the Bren Ten pistol, was based on a cut down 30 Remington case, and that is where the large primer came from. When S&W cut the 10mm down and developed the 40 S&W from it, they dropped the primer size down to the small primer, possibly because of case volume.

 

[Leo77c]

Mor powder would be my g3

 

[ZX9RCAM]

Welcome to the Forum!

 

[Mike_from_Texas]

Because 40 is gay.


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[Texas45]

Because 40 is gay.


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But yet not as gay as 9mm.


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[sergeant69]

everytime i come across a SP 45acp case i crimp it shut w/pliers and chuck it. you're welcome

 

[SQLGeek]

But yet not as gay as 9mm.


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The ancient Europellet laughs in your general direction.

 

[Vaquero]

everytime i come across a SP 45acp case i crimp it shut w/pliers and chuck it. you're welcome

I keep them and reload them.
Used on range days at public ranges.

 

[SQLGeek]

everytime i come across a SP 45acp case i crimp it shut w/pliers and chuck it. you're welcome

They should be cast back into the pit of hell from whence they came.

 

[Texas45]

I keep them and reload them.
Used on range days at public ranges.

Yup just sort small / large prior.
They work just fine.


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[Texas45]

The ancient Europellet laughs in your general direction.

Laugh away.
40/45 hand guns for me
38/357 wheelies.
Nothing in the europellet size.
Sorry.
Been shooting long enough to learn to manage the bug bore handguns

Try it sometime.


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[SQLGeek]

I guess you didn’t see this that I posted yesterday.

I’ve more than “tried it”!

I love the big bores. I just am amused when people trash 9mm because reasons.

Only .357 in wheel guns? You need a big, manly .44 in your life. .357 is only .001” larger than the ghey 9mm!!

 

[Texas45]

I guess you didn’t see this that I posted yesterday.

I’ve more than “tried it”!

View attachment 238262

I love the big bores. I just am amused when people trash 9mm because reasons.

Only .357 in wheel guns? You need a big, manly .44 in your life. .357 is only .001” larger than the ghey 9mm!!

I dont own a 44mag but I got t good buddy with a Ruger 45LC I shoot all the time.

Same thing for me and 40 amused by ya know reasons. .

Ive also had the pleasure of a 454 casull wheelie and a desert eagle 50

Personal choice not to hop an the 9mm bandwagon I guess.


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[BigTexasOne]

While we're on the subject, the small vs large pistol primer issue in .45acp absolutely pisses me off! Every once in a while one of those damned little primer cases will get past me, through the decapping die, and over to have a new primer installed, obviously a large primer won't fit, but the press will try to jam it in there and a primer gets wasted because now it's deformed.

Who ever it was that thought it was OK to make small primer .45 acp cases should be taken to the range and used as a target, jmho!