Large Pistol Primer vs Small Pistol Primer on 45 acp

Ive discarded all SPP 45 ACP for many years. But have loaded some with SPP in the past.

Ive used Winchester 231 to test both ww LPP and ww SPP loads using the same charge, under the same 230 gr. FMJ. Saw NO difference whatsoever in velocity or performance.
That was my only test where there was measurable evidence of any kind.
If there is differences in different combinations, which is very plausible, I do not know that.

Hope this helps.

I, too, have found no difference.
I first noticed SPP during the 1st obamanation scare.

I chronographed 'em & found no speed difference, and accuracy was just fine.
I have enuff of both to keep em.
My SPPs are all Blazer & I do separate by head stamp so they're easy to keep.

One is made the way it should be.
The other has a smaller primer hole...

I, as well, found little meaningful chronograph difference and standardized on the large primer.

At times like these, there may be advantages to keeping a supply of both...

Until this primer shortage I used them both equally—several thousand of each and noticed no difference. But, that’s for the mere 6 months I’d been loading until everything dried up. Now my SPP stash is only for my 9mm.

My side by side testing with identical loading showed so little difference it didn't really matter to the average shooter. I bought 100 small primed cases, mixed headstamp and compared the loads to 100 mixed headstamp large primed cases. In my 3, 45 ACP guns the only difference was a slight slower (20-25 fps?) measured velocity, but that could have been me, the chrony, or the weather/sun. Perhaps an experienced Bullseye shooter could find an appreciable difference, but for all intents and purposed, same-same...

I am running short of large pistol primers (just 2,500 left) so I bought an additional 300 small primed 45 ACP cases...

"....You gotta keep em separated!!!.....hey!!!"

2 resources;

https://www.starlinebrass.com/articles/small-pistol-primers-vs-large-pistol-primers/

https://www.shootingtimes.com/editorial/small-vs-large-pistol-primers-45-acp/99626

Interestingly enough. When powder valley did their black Friday sale on Remington 1.5's for $20 power thousand i specifically purchased for 45acp spp application. I didn't like the wording on their box about low pressure loads only which to varying degrees puts 9mm into high pressure.

Any way you look at it I've reloaded my 45acp blazer brass at least six plus times with outstanding results.

I started like everyone else with the lpp brass, and found a few spp brass cases at the range while I scavenged. After a little while I had enough to load up a box of 50 with spp so I did. For just range plinking they showed no real difference and I started using app because I only had to buy one kind of primer. Now I will load and shoot lpp till I'm out, because spp are way more versatile.

I have found that the SPs work just fine, maybe 30fps or so slower than the LP ones.
I was using WIN LPs for the LP cases (fairly hot LP) and S+B SPs(mild for SPs) for the small SP cases.
S+B SPs tend to be about 15-20 fps slower than CCI SPs so given the different primers I used it's going to be closer between the two most likely.
Unless you are loading MAX loads (in which case I would work up again) your LP load should work fine in a SP cases.

The SP ones can be a pain (for some reason LPs just don't want to seat in them no matter how hard you try) but it is nice to have them around in case you are out of LPs.
The one advantage I can see would be only having to have SPs and not having to change your priming setup if you load other things with SPs and are setup to prime SPs already.
Otherwise it's a wash IMHO.

AJC1 said:

I started like everyone else with the lpp brass, and found a few app brass cases at the range while I scavenged. After a little while I had enough to load up a box of 50 with app so I did.

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I'm just trying to gain knowledge from this. Exactly what is "app" ?

Would guess the poster meant spp not app, darn a key is right by the s

There is no performance issue. It is just Federal being an idiot and making reloading more difficult for us.

I have not shot at a range where I had an opportunity to pick up range brass in decades. So, as far as I'm concerned, they are "fake news" and do not exist since I've never seen one.

I would not expect any difference in performance that I could see.

Seriously, if a small pistol primer 45 ACP case did get into my mix, I'd trash it. It would be a pain to keep the cases segregated.

If small pistol primer 45 ACP cases became the standard, I'd embrace them but it would take me a long time to consume all the large pistol primer brass that I have on hand.

cfullgraf said:

I have not shot at a range where I had an opportunity to pick up range brass in decades. So, as far as I'm concerned, they are "fake news" and do not exist since I've never seen one.

I would not expect any difference in performance that I could see.

Seriously, if a small pistol primer 45 ACP case did get into my mix, I'd trash it. It would be a pain to keep the cases segregated.

If small pistol primer 45 ACP cases became the standard, I'd embrace them but it would take me a long time to consume all the large pistol primer brass that I have on hand.

Click to expand...

It's a thing where I only shoot one type at a time for exactly that reason. It's not exactly a pain because I sort by headstamp already.

Kevin Rohrer said:

There is no performance issue. It is just Federal being an idiot and making reloading more difficult for us.

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It’s not just federal. Also Speer, blazer, maybe more.

I just save the spp 45acp for hard times. I find them when the LPP refuses to go into the spp hole as dudedog said!
Hey we are in hard times now!
Time to drag them out n load em up! Right along with my spp AL cases!
Ye ha!

The loads I've tested (Bullseye with 230 grain bullets) function equally well with lpp and spp.

I save those nasty spp cases for lost-brass events. They protect me...from my irresistible desire to bend over and pick them up.

I vaguely recall reading an article when I was researching .400 Cor-Bon; essentially 45 acp cases loaded to higher chamber pressure had fewer issues with primer flattening using small pistol primers in cases made to accommodate them. I never loaded any spp cases so can’t say.
Reading the OP made me think spp 45acp cases may not have been as a performance enhancement for 45acp but for broader use reforming cases for .400 Cor-Bon. Niche thing.
I believe.400 Cor-Bon never reached the popularity some hoped for. I have fun with it.
Maybe someone can help in citing the article

I just found another 45 small primer—WIN NT.

I have about 1000 of various brands cleaned up and just waiting for 2024.

Why 2024 you ask? That’s when small primers will be readily available at less than .15 each.

cfullgraf said:

Seriously, if a small pistol primer 45 ACP case did get into my mix, I'd trash it. It would be a pain to keep the cases segregated.

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For OCD types, you need to separate both by HS and primer size. If you’re fortunate enough to purchase a single size primer for .45 and then recover and only reload those, then you don’t need to worry. I’m one of the range recovery brass squad so it’s second nature to separate .45s in two ways.
All of my data from SPP and LPP shows no appreciable difference.
The nice thing about stocking both size primer cases, if you have only one press you can load whatever primer size is set up and not have to change that. Good luck.

I load them both. Don't see too many new small ones. I have never found any difference in performance. Other, than the primer, I load them exactly the same. Best wishes!

Jeff62 said:

View attachment 957510 I vaguely recall reading an article when I was researching .400 Cor-Bon; essentially 45 acp cases loaded to higher chamber pressure had fewer issues with primer flattening using small pistol primers in cases made to accommodate them.
Maybe someone can help in citing the article

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The 450 SMC uses a small primer for the same reason. The 45 Super uses large primers but can have excess primer flow but the problem is solved by using small primers in the (higher pressure) 450 SMC.

I bought a case of SPP some years ago... and shortly after pretty much gave up on loading anything that used SPP's. So I picked up a batch of once-fired .45 with SPP pockets. Aside from the need to... keep 'em separated... I've found very little difference against LPP.