.45acp small primer vs large primer brass

[avcrew]

I wanted to know if there was a difference.

Did a test. Thought I'd post my results for those wanting to know the same.

Test #1:
Bullet: Berry's 230 grain plated
Powder: 5.3 grains HP38
OAL: 1.235"
Gun used: Kimber full size 1911
Primers: Winchester small and large pistol

10 shot averages:
Winchester small: 779 FPS
Winchester large: 817 FPS
Difference: 38 FPS

Test #2:
Bullet: Missouri 200 grain LSWC
Powder: 4.2 grains Bullseye
OAL: 1.24"
Gun used: Kimber full size 1911
Primers: Winchester small and large pistol

10 shot averages:
Winchester small: 779 FPS
Winchester large: 793 FPS
Difference: 14 FPS

Different powders, primers and bullets will yield different results but there definitely was a difference in these two "go-to" loads of mine. Test #2 yielded the least FPS difference. It's possible that a faster powder like Bullseye is less sensitive to primer size.

[maxx03]

I have found that the small primer brass has more uniform flash holes and my loads are more accurate.

[Whiterabbit]

Two things.

#1 Mean shift doesn't matter, unless you're talking about hitting some level of power. What I have found is that primer choice has an enormous impact on group size, but that's hard to quantify in a handgun.

#2 Mean shift and even ES shift will be noticed even switching brands of primer. The shift you are measuring may be within the noise of switching, for example, Winchester vs CCI primers. Or not. Not sure without data.

Combine those two above and it makes me wish I had access to high quality 243 win small primer brass (I know I can form it from 308). Because I was able to measure large improvements in performance as I got weaker and weaker primers. Today I load large pistol primers in my 243 cases, and even then the ones the internet tell me have "the least fire". Sounds odd, but the benefit is measurably better. Maybe not so much in your gun. My 7x57 saw measureable improvement switching to magnum primers. Go figure. Too bad too, it's hell on the bolt face. my 243 is probably pristine.

[rm1911]

SPP 45acp brass is the work of the devil.


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[mjmagee67]

I recall a roughly 20fps difference between SPP and LPP brass.

I use to like and load a lot of SPP 45 because I didn't have to change over the priming systems on my progressives. Now that I got a progressive just for Large Primer I'm back to loading only LPP 45....sorting is always a pain in the donkey.

[Mayor McRifle]

SPP 45acp brass is the work of the devil.

I agree.

Those are interesting results, though. Barring further information, I’d say don’t use SP and LP .45 brass interchangeably with a particular load. Thanks for posting your data, OP.

[robert101]

Thank for the work OP. Good information. Personally, I throw the SPP brass away went found as it is an annoyance. To those who see the benefit = go for it.

[Bobshouse]

I found that crushing a large primer when trying to insert it into a small primer pocket will often end up with ignition.

[avcrew]

I have a gallon ziplock full of the small primer brass.

Did the test and now the question is what to do with it.

Does it reload? Yes.

Does it use the same recipe as large primer brass? No.

Do I have to ton more large primer brass to use? Yes.

If i hold on to it, the only time I would start reloading it is if I ran out of large primer brass, and if I ran out of LP brass, I think we all have bigger problems.

[XDJYo]

SPP 45acp brass is the work of the devil.


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+1,000,000,000


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[CAL.BAR]

I found that crushing a large primer when trying to insert it into a small primer pocket will often end up with ignition.

WOW - you're pulling the lever waaaay to fast then. Primers only ignite with IMPACT, not crush.

[bruce381]

WOW - you're pulling the lever waaaay to fast then. Primers only ignite with IMPACT, not crush.

wrongo I have blown primer tube twice when trying to stick and large primer into a small primer hole.

Learned my lesson now stop pushing when the primer hangs up

[Ironfether]

wrongo I have blown primer tube twice when trying to stick and large primer into a small primer hole.

Learned my lesson now stop pushing when the primer hangs up

[FresnoRob]

I recall a roughly 20fps difference between SPP and LPP brass.

I use to like and load a lot of SPP 45 because I didn't have to change over the priming systems on my progressives. Now that I got a progressive just for Large Primer I'm back to loading only LPP 45....sorting is always a pain in the donkey.

This is the only real reason to use it.

[bruce381]

Read my post after this:

Originally Posted by Bobshouse View Post
I found that crushing a large primer when trying to insert it into a small primer pocket will often end up with ignition.

WOW - you're pulling the lever waaaay to fast then. Primers only ignite with IMPACT, not crush.

I'm saying its not speed but crush will set them off also