Small Primer vs Large Primer Comparison

[J. Frank Norfleet]

Someone asked how did small primer 45 acp compare to large primer 45 acp velocity/power factor.  I had a chance to run a comparison last week.  Used the same machine to load all 4 test loads.  The only thing I changed was the primer feed.  The Winchester small primer magnum loads were the big surprise.  See the pdf below.

JFN

SP_vs_LP.pdf

[Tully Mars]

JFN,

Thanks for the information. Not what I would have expected.

Tully

[DUSTY BODDAMS]

JFN, an interesting read for sure!  that information could really help someone from power factor failure

[VICIOUS]

I thought that the Winchester SPM primers felt better, but figured it was a head thing. WOW I aint losing it.

[August West]

Since small pistol primers in the .45 a.c.p. are such a vexation to me, it saddens me to read discussions that justify their existence. Sigh....

[Garrison Joe]

+1 for AW.

 

I still don't believe their existence is justified.  Even if we have data saying small primers in these new cases work OK, we don't have data saying this is a good idea for the redesign of ammo that has been standard for about 105 years now.  Most deviations from standards in the firearms industry usually end up hurting someone.  That is one reason SAAMI was set up in 1927.

 

But at least I've not blown up a Dillon press more than once with large primers being seated into small primer pockets, as one of our pards has reportedly done.  Mine just slams to a halt.  So far.

 

Good luck, GJ

 

[Blaze Kinkaid 253]

  After an illuminating discussion with my mentor August West, I have destroyed any and all .45 ACP brass in my possession  that utilized a small primer.    Augie you can relax now!  :) :)  Blaze

[J. Frank Norfleet]

AW & GJ sorry for the misunderstanding.  I posted the above for information only.  Since I shoot primarily small primer brass, I have been asked if there is a difference in velocity.  While I felt that small primer brass lowered the velocity, I had never compared them side by side.  My only fallacy in the test is that the primers are not all from the same manufacturer; as, I am now wondering if all Winchester primers are "hotter."

 

So let me be clear.  I don't feel the need nor compunction to justify a superior brass to you or anyone else. :)

JFN

[Boggus Deal]

AW & GJ sorry for the misunderstanding.  I posted the above for information only.  Since I shoot primarily small primer brass, I have been asked if there is a difference in velocity.  While I felt that small primer brass lowered the velocity, I had never compared them side by side.  My only fallacy in the test is that the primers are not all from the same manufacturer; as, I am now wondering if all Winchester primers are "hotter."

 

So let me be clear.  I don't feel the need nor compunction to justify a superior brass to you or anyone else. :)

JFN

 

8) 8) 8)

[Kid Rich]

AW & GJ sorry for the misunderstanding.  I posted the above for information only.  Since I shoot primarily small primer brass, I have been asked if there is a difference in velocity.  While I felt that small primer brass lowered the velocity, I had never compared them side by side.  My only fallacy in the test is that the primers are not all from the same manufacturer; as, I am now wondering if all Winchester primers are "hotter."

 

So let me be clear.  I don't feel the need nor compunction to justify a superior brass to you or anyone else. :)

JFN

I sort my acp brass and then load all the sp at the same time. Last time was 600+.  kR

[Griff]

AW & GJ sorry for the misunderstanding.  I posted the above for information only.  Since I shoot primarily small primer brass, I have been asked if there is a difference in velocity.  While I felt that small primer brass lowered the velocity, I had never compared them side by side.  My only fallacy in the test is that the primers are not all from the same manufacturer; as, I am now wondering if all Winchester primers are "hotter."

 

So let me be clear.  I don't feel the need nor compunction to justify a superior brass to you or anyone else. :)

JFN

8) 8) 8)

Aye, just how much difference is there between WLP & WSP primers.

 

And while I abhor the fact that my press slams to a halt, (ok, so it just interrupts my process), when it encounters a SP hole that slipped thru my sorting process... let us not forget that well beyond the advent of SAAMI, the ubiquitous .38 Special was formed in cases using a LARGE primer...  So it's not like there isn't a precedence for changing a cartridge from big to small primers.  Just give me a reason that justifies such change besides, "it's good for the environment..."  Because yoohoo... we introducing LEAD into the ground... Oh wait... that's where it comes from!!!

 

JFN, superior in what way... I'll grant you that the smaller primer hole might make for a stronger case...  But, if there's any significance to the difference might be arguable.

[J. Frank Norfleet]

Griff,

At the risk of "justifying their existence" I will answer your question.  The main reason I like SP brass is it is much easier to load, specifically to prime than LP brass.  I seem to have zero problems with high primers and primers that are difficult to seat.  Second, I find that SP loads are more consistent in velocity, a narrower spread from high to low.  Third, I can buy once fired SP brass way cheaper.  Fourth, SP brass has a heavier web.  When you cut one in half, the web and sidewall at the base are thicker like a 45 GAP or a Starline +P.  Which should make it stronger in unsupported areas.  LP brass runs 78-79 pieces a pound while SP brass runs 72 pieces a pound.

 

As a side note, I have found that my 45 ACP '73 rifle needs nearly new LP brass to run well and fire every time.  But, use any SP brass and problems go a way.

 

I have a 5 gallon bucket full (5000+ pieces) that is half way through its 10th reload.  I try not to take it to the local matches unless I am out of LP loads.  That is my practice brass.  If I have to use it (like last month) I warn every one to check their brass carefully, because I know a lot of shooters don't like it.

JFN

[Garrison Joe]

I have found that my 45 ACP '73 rifle needs nearly new LP brass to run well and fire every time.  But, use any SP brass and problems go a way.

 

Sure sounds like a too-light firing pin strike is occurring on the '73 that has been rechambered to .45 auto.  Small primer might have a more rigid anvil than a large primer design does, due to "bigger span" of the LP anvil's arch? 

 

It's not the outside dimensions of the .45 auto case that varies between the NT (non-toxic) SP case and the original design of the LP case.  If you taper crimp both the SP cases and the LP cases the same way, then it's not likely that the gunsmith cut the .45 chamber too long (bad headspace, thus letting the round slide forward on firing pin impact).  The only thing different is going to be the primer and the pocket.  SP primers MAY be a little more sensitive to a FP strike than LP primers.  I've not seen anyone run that test yet.    Would be interesting to see, when using exactly the same brand of primers, whether SPs are easier to light off as the main spring tension is backed off.

 

There's a tremendous number of cowboy type shooters who over the years have claimed that a particular gun after it was tuned up for lighter spring weights, would no longer run anything but Federal primers.  This sounds a lot like the same story, just in a different suit.  I'd bet the lack of reliability of firing can be resolved by tuning hammer fall to be a little heavier, as has been the case in hundreds of cowboy guns I've heard about and a few I've even tinkered with.

 

Good luck, GJ

[J. Frank Norfleet]

Joe, Chased all those rabbits and then some more.  My statement still stands.

JFN