Small primer vs large primer same case.

Waterboy3313

Waterboy3313

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I'm just curious is anyone has noticed using small primers is what is normally a large primer case? I started loading 6.5 creedmoor back when large rifle primers were non existent on the market so I ordered small primer cases as I had small rifle primers on hand and that has been my only experience with that cartridge.

Over the years I have collected my share of range brass and I have started getting quite a bit of small primer 45 acp and 10mm auto cases on a fairly regular basis. I normally separate it and process it and keep it separated. I'm getting ready to start a new and completely different 45 acp work up. I guess the question will answer itself when I get around to testing but I am curious to any difference in performance.

I figured since I will be trying a completely different bullet weight and profile as well as a different powder I would try the small primer cases. Because everything will be so much different I won't notice anything different anyways. It's just one of those stupid what ifs in the back of my mind I probably shouldn't waste my time thinking about. Curiosity killed the cat and does get my attention. Any personal experience would be greatly appreciated.
 
Waterboy3313 said:
I'm just curious is anyone has noticed using small primers is what is normally a large primer case? I started loading 6.5 creedmoor back when large rifle primers were non existent on the market so I ordered small primer cases as I had small rifle primers on hand and that has been my only experience with that cartridge.

Over the years I have collected my share of range brass and I have started getting quite a bit of small primer 45 acp and 10mm auto cases on a fairly regular basis. I normally separate it and process it and keep it separated. I'm getting ready to start a new and completely different 45 acp work up. I guess the question will answer itself when I get around to testing but I am curious to any difference in performance.

I figured since I will be trying a completely different bullet weight and profile as well as a different powder I would try the small primer cases. Because everything will be so much different I won't notice anything different anyways. It's just one of those stupid what ifs in the back of my mind I probably shouldn't waste my time thinking about. Curiosity killed the cat and does get my attention. Any personal experience would be greatly appreciated.
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If you find small primer 30-30 your a lucky guy... the increase in powder to make up for the reduction in primer power seems like a fine solution...
 
When I inherited the Marlin 336 my grandfather bought new in 1964 30-30 ammo was impossible to find anywhere local to me. I always wanted to handload for it but the large primers were nowhere to be found either. I get it out about once a year and run about 5 rounds through it and put it away. The sentimental value of it always puts a big smile on my face and good memories always follow.
 
Years ago when I first started shooting 45ACP I was buying factory ammo at Wally World until I got my dies and other stuff to start reloading. If I bought a 100 round box they would be LP. If a 50 round box they would be SP. For whatever reason.
 
I picked up a bunch of 308 small primer just because SR are always easy to get
 
All my 45ACP brass now is LP. If I had it to do over again I would get SP 45ACP so that when I change my Dillon 550 from 9MM to 45ACP I wouldn't have to change the primer set up. But even at that it's not a big deal.
 
Want list. Small primer 10mm , 7.62x39. Have SP 45 auto and .308
 
I have only done a little playing with 45acp LPP vs SPP, but have not been able to shoot a difference between the two. In rifle cartridges, I have used Lapua Palma brass for all 308win family cartridges for a long time, over 20 years, and now have both large and small primer 6 Creedmoor brass - when I was really beating on my brass, the thicker head of the small primer brass lasted longer, but I don’t load that high pressure for many purposes any longer.

Load data interchangeability between the same brand with small vs large primer pockets is hit and miss, not all brands have consistent internal capacity between these different runs.
 
JFrank said:
Large rifle primers might be a bit more reliable in very cold conditions. No scientific proof, also the military specs LRP for 5.56 so there must be a reason
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It's OK to say they have proof. In fact Peterson brass has a warning .
For me target ammo isn't balls to the wall so 45 auto ,10mm and x39 SP is just fine. .308 just cause I wanted volume for a LAR 8 and large rifle primers were running short. And using old fashioned easy igniting 3031 it has worked great.
Balls to the wall is an extremely manly saying if you know where it came from.
 
For .45 ACP the difference between large primer and small primer is so insignificant as to get lost in the noise of everything else. When I started loading .45, I deliberately sought out the dreaded small primer brass so I wouldn't have to stock different primers. I've seen some argue that large primer .45 might be more reliable if you have a firing pin that hits off-center, but I'd argue a gun with a firing pin that off center needs to be fixed.

I thought about picking up some small primer .308 Winchester brass, then hesitated because I like to shoot in the cold and sometimes use ball powders. Perhaps with component availability improving I should get some small primer cases to try out and see what happens.
 
entropy said:
Which military? The one I was in had SRP in all it's NATO standard 5.56 ammo, both M193 and M855.
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I've seen you make mistakes. Ive had mistakes. We could start a list of names and dates around here so let's just drop it. All in fun right. Move on to bigger fish . just a thought.
 
I'm thinking he miss typed and was thinking 7.62x51:), I can't reply about that since I don't reload that cartridge.

I've always thought you could get longer case life using a SRP case when loaded close to max, I load 6.5CM and use a SRPM in the SRP cases and haven't noticed a difference out to 600yrds vs a LRP case. In 45acp I definitely can't tell a difference and started loading all my lead bullets with SPP brass. I just picked up some 6CM brass and it is SRP so I won't have anything to compare them to.
 
I was just curious if anyone noticed any kind of difference was all I was interested in. I was pretty sure the real difference would be undetectable by the average shooter. I did read one of those stupid you finish the sentence/statement things somewhere else a while back. It went something like "This is something you shouldn't have at your reloading bench....".
A lot of the answers were small primer 10mm and 45acp cases.
I would assume most people were just making fun but I do know some people wouldn't have it just because of tradition.
 
Online tests show the small primer causing rifle problens in cold weather. The small in 45acp, produces lower velocity . No need for me to change from the old, proven ways.

Change is not always better. See Starline Brass test of the 45acp
 
More than 20 years ago now but when I first came across them and Winchester was making at least 3 different 45 ACP cases, I tested the large/small flash hole 45 ACP brass and SPP. The larger flash hole gave slightly lower ES/SD but I only tested with one powder/charge weight (Clays) and the sample size wasn’t very large. Close enough to the same the time spent/reward isn't there for me but that's competing in uspsa/idpa type games.

F80AA978-081E-415C-9C22-4887F0EDCF6A.jpeg
 
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