How can one tell the difference between a large and a small pistol primer in .45 ACP brass? I have numerous different brands of brass. Is there some way to physically measure to make a determination?
How to tell the difference
- Thread starter Fox Mike
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I don't know other than trying a small primer in each one , if it drops in it's large. That would drive me nuts keeping those separated I try just to use large for no particular reason and when I come across small I put them in a sealed marked container and don't reload them. some day I might switch if I run out of reloads
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It should be visually obvious, it is to those who've been hand loading for any appreciable amount of time. But if it isn't to you, take a 9mm case & use it to compare to a .45 case. Looking at the head stamps of both, the 9mm uses a small pistol primer which will visually match in size to any other case using the same. You can measure the width of the primers if you want to, but once you get used to looking at .45 head stamps it becomes obvious when you're looking at one that uses a small primer.
Primer pocket cleaners come in large and small. Obviously, the large cleaner won't enter a small pocket. . 
I look at them and put them in the correct marked brass box. It might help to have 2 cases nearby with 1 a large the other a small to look at also.
My experience was that CCI Blazer brass went to small primers first, so, depending on what's happened since, you might be able to sort by brand with reasonable accuracy.
Posts # 3 and 4 
OP
Well since I haven't been handloading at all is why I asked the question. The first 50 casings I looked at seemed to be the same but that really tells me nothing as they could all be large or they could all be small..Is there a dimension that can be physically measured?
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Sure, get a case that only uses small primers, like a 9mm, .380, .38 or .357, .40 S&W, etc. & measure the width of the primer, then measure the .45 case you have. The ones using a small primer will have the same diameter than the .45 if it's using a small primer also. If the .45 primer width you have is larger than the 9mm, etc ...your .45 has large primers. You may be able to Google for the width dimensions for each type but I've never searched for that.
Give me a minute & I'll measure some I have
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OP
3manfan, thanks that will help
contender
Ruger Guru
I would measure actual spent primers to get correct measurements. Then compare that measurement to a box of new primers,, which will be marked either large or small.
Frank,, your question is valid. But as Ken said,, re-read posts 3 & 4. Once you get an example of a small primered .45 case,, you'll see it quite easily.
Frank,, your question is valid. But as Ken said,, re-read posts 3 & 4. Once you get an example of a small primered .45 case,, you'll see it quite easily.
OP
OK, one last goofy question (ya only get answers if you ask questions). Are small rifle primers the same size as small pistol primers? If so then I have something to compare as I have small rifle primers.
NikA
Hunter
Yes, they are. Both small and large primers are the same diameter between rifle and pistol, large rifle primers are taller (deeper primer pockets) than large pistol primers.
Nika, I read somewhere, that LARGE pistol and LARGE rifle are NOT the same size. (Don't recall if the difference in size was diameter or depth).
p.s. the source was one of the nationally known authors on reloading IIRC
J.
contender
Ruger Guru
As noted above,, the small rifle & small pistol primers are the same diameter.
As for the large rifle & large pistol primers,, for the purposes of comparison between large & small, you can use either one to compare it against a small primer.
As for the large rifle & large pistol primers,, for the purposes of comparison between large & small, you can use either one to compare it against a small primer.
This past weekend I mentored my Friend on reloading a gaggle of spent .45 ACP brass, I had sorted through the brass and pulled the small pistol pocket 45's... yet we did run into some issues when we encountered military 45 brass, those would not accept large pistol primers.
He got through just under 400 rounds before he ran out of bullets; he still has 400+ cases to reload; I sorted through the remaining 400+ and pulled another 5 military cases so when he comes back he'll be able to reload without resistance
One last observation, not all brass has standardized flash holes; Norma 9mm brass has smaller than normal flash holes which would require thinner sized pin to punch out spent primers, I don't think their 45 ACP has that as I've reloaded those cases in the past though it was a smaller number of Norma brass.
He got through just under 400 rounds before he ran out of bullets; he still has 400+ cases to reload; I sorted through the remaining 400+ and pulled another 5 military cases so when he comes back he'll be able to reload without resistance
One last observation, not all brass has standardized flash holes; Norma 9mm brass has smaller than normal flash holes which would require thinner sized pin to punch out spent primers, I don't think their 45 ACP has that as I've reloaded those cases in the past though it was a smaller number of Norma brass.
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NikA
Hunter
J., read my post. Diameter is the same, height is different.
Fire Chief
Bearcat
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Here are one of each that have been de-capped.
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