Large Pistol Magnum Primers vs. Large Pistol Primers

[That Guy]

I've tried to google this, but the discussions I've found elsewhere have been so devoid of actual information that it's driving me crazy. Perhaps you guys could help me out here?

In my country, the shipping regulations make it basically impossible to have primers shipped to you. Even picking them up yourself, there is a hard limit on how many they can sell you at a given time. I am all out of large pistol primers, but I have a box of magnum primers that I bought by mistake some time ago. Because of the current situation I'd like to use these instead of making a road trip for the express purpose of a single box of primers. But can I?

The gun I am loading for is a Smith & Wesson Mountain Gun in .45 Colt. I have previously worked up a load that launches plated 250gr bullets at 900fps using Magtech large pistol primers, and VV N-340 powder. I'd like to more or less duplicate this load, but using the aforementioned magnum primers.

Some people on the Greater Internets claim magnum primers are interchangeable with regular ones, others that one should drop the powder charge by one grain (strangely enough it matters not how much and what kind of powder the previous load was, the answer is always "lower one grain"...), and yet others claim that any deviation from published load data (no matter how reliable the publisher, or whether the publisher themselves have later deviated from the previous data...) is unpossible. I find myself somewhat sceptical of all these opinions, especially since nobody ever says why they think they are right.

[mtnbkr]

It varies by primer, but by and large there's not a huge difference. The reason for dropping the charge 1 grain is to compensate for any sort of pressure differences that my result, but you are free to work the load back up to the previous levels after dropping it. Sometimes using a mag primer *might* increase your groups, but sometimes might improve them. Some powders work better with standard primers (anecdotally, Alliant 2400 in mag loads).

I've seen a couple tests that show (via high speed camera) that some mag primers are a little hotter (longer, thicker...er flame). However, when I've used mag instead of standard, I've noticed no difference in firing or performance on paper.

FWIW, Winchester Large Pistol Primers are listed for "Standard and Magnum Loads" and they don't offer mag primers in that size.

Use a tighter crimp, I have heard reports that using a mag primer *might* cause the bullet to start moving before the powder is fully lit, but I don't know how scientific that statement is.

Chris

[That Guy]

Oh, right, it might help if I actually mentioned the specific primers too?

Old primers were, like I said, Magtech large pistols. New ones are CCI 350's.

[Lester Polfus]

I mistakenly purchased a bunch of magnum large pistol primers back when I was reloading 10mm. I just worked my load up from scratch (200 grain bullet over Longshot) with no issues. I wound up at the same exact max powder charge. I do think I had a higher standard deviation, but it didn't matter for accuracy.

[okie john]

I just worked my load up from scratch (200 grain bullet over Longshot) with no issues. I wound up at the same exact max powder charge.

I’d do this. You’re near the top end for VV-340 with a 250. Some powders get spiky and weird when pressures are high. Best to play it safe.


Okie John

[nwhpfan]

Wow, 250g at 950 fps :)

So I've loaded a couple thousand CCI 350 in place of CCI 300. I noticed zero difference on the chrono, performance, brass markings, etc.

I had a guy that gave me a box and a half, or maybe 2 or more boxes, I don't remember. I recall wondering the same thing as you; was it OK. I searched and found everything from no difference to drop a tenth to you shoot your eye out. I was shooting 3.8 Clays and 230g coated RN at that time.

I hope this helps.

[45dotACP]

I've used magnum primers in some standard calibers as well. I noticed no difference in pressure signs, but have no access to a chronograph.

Sent from my moto g(6) using Tapatalk

[fatdog]

I have loaded both Federal magnum and standard large pistol primers in .45ACP and .45LC and I cannot detect any difference with smokeless powders, Bullseye, Titegroup, N350, N320, Trailboss. I have seen measurable differences between different lots of powder however.

With black powder in .45LC I get a bit more consistency with the magnum primers, especially my 3F loads.

[Mirolynmonbro]

I loaded small pistol magnum primers and the FPS increased by 10-15. But, never loaded large magnum before

[mikld]

As mentioned above, and for safety sake, just do another load work up. Early on in my reloading I experimented with using "different" primers than what was "common" (1970-1980). I used many magnum primers in standard primer applications, but I rarely got close to max loads. In a situation where components are hard to find and one doesn't want to "waste" any, just drop your present powder charge and test (one to two grains depending on hop close to max it is)...

[Jim Watson]

Small primers whether rifle or pistol, standard or magnum, made no difference in 9mm with HP38 except that Remington SP gave higher velocity than any other.
Large magnums boosted velocity in .45 ACP + Bullseye a bit, but that was CCI magnum vs Federal standard, which is another source of variability.

[SecondsCount]

My experience was the difference between standard and magnum small rifle primers. I don't run my loads near max but I saw very little change between the two, 20 FPS, in 223. With small rifle primers, the biggest difference is in the cup thickness.

If the thickness difference applies to the large pistol magnum primers, you may want to be certain that your gun is capable of igniting them.

[5pins]

Years ago I was experimenting with some woods loads for my 1911 in .45 ACP using Ramshot Enforcer powder. Their load manual at the time listed over 1000fps with a 230-grain bullet. When I tried duplicating their load I was coming in much lower. So I tried out some Federal, and CCI magnum primers to see if it made any difference. The CCI magnum primers were getting me about 40fps more velocity with max loads. The Federal, on the other hand, showed no change over standard primers.

That data has since been removed from their load manuals but I was getting over 1000fps with a 230-grain bullet and 1100fps with a 200- grain.

[ViniVidivici]

I have used magnum small pistol primers in place of standard with 9mm and .40 many times, no issues.

[Trooper224]

There will be no functional difference between standard and magnum primers. Winchester pistol primers are labeled, "For standard or magnum loads", ever wonder why that is? Magnum primers aren't hotter than standard primers, they just burn longer. They're designed to be used with slower burning powders in order to get a more complete burn on the powder charge. The "magnum" name is something of a misnomer, as it gives users a false assumption. Unless you're using a slower powder along the lines of Alliant Blue Dot a magnum primer isn't needed, nor will it make any difference if you substitute them with faster burning powders.

Now, try mistakenly using rifle primers in your handgun loads and have about a quarter of the batch require a second or third strike to ignite, that's irritating.

[Clusterfrack]

There will be no functional difference between standard and magnum primers. Winchester pistol primers are labeled, "For standard or magnum loads", ever wonder why that is? Magnum primers aren't hotter than standard primers, they just burn longer. They're designed to be used with slower burning powders in order to get a more complete burn on the powder charge. The "magnum" name is something of a misnomer, as it gives users a false assumption. Unless you're using a slower powder along the lines of Alliant Blue Dot a magnum primer isn't needed, nor will it make any difference if you substitute them with faster burning powders.

Now, try mistakenly using rifle primers in your handgun loads and have about a quarter of the batch require a second or third strike to ignite, that's irritating.

Good post. During the Hillary panic and resulting components drought, I substituted small pistol mag primers for several thousand rounds of 9mm, and couldn't measure any velocity difference.

I use military rifle primers (CCI-41) in 9mm loads to test whether the hammer springs in my P-07s are heavy enough.

[19852+]

I have used magnum small pistol primers in place of standard with 9mm and .40 many times, no issues.

My experience also, no issues, no difference. I was told once that magnum primer was designed for more complete ignition of larger charges. Not sure how this is done and they look exactly the same to my eye.
However, I have gotten responses from the powder, primer co's out there to my emailed questions.

[358156hp]

There will be no functional difference between standard and magnum primers. Winchester pistol primers are labeled, "For standard or magnum loads", ever wonder why that is? Magnum primers aren't hotter than standard primers, they just burn longer. They're designed to be used with slower burning powders in order to get a more complete burn on the powder charge. The "magnum" name is something of a misnomer, as it gives users a false assumption. Unless you're using a slower powder along the lines of Alliant Blue Dot a magnum primer isn't needed, nor will it make any difference if you substitute them with faster burning powders.

Now, try mistakenly using rifle primers in your handgun loads and have about a quarter of the batch require a second or third strike to ignite, that's irritating.

Hopefully your gun won't even chamber loads with rifle primers. Large rifle primers are taller than large pistol primers and the slide on semiautos should not go into battery, although I suppose there's potential for the slide hitting the protruding primer hard enough to ignite it. Revolver shouldn't even allow you to close the cylinder with large rifle primers in the cylinder.

SR & SP primers are dimensionally identical externally.

[Trooper224]

Hopefully your gun won't even chamber loads with rifle primers. Large rifle primers are taller than large pistol primers and the slide on semiautos should not go into battery, although I suppose there's potential for the slide hitting the protruding primer hard enough to ignite it. Revolver shouldn't even allow you to close the cylinder with large rifle primers in the cylinder.

SR & SP primers are dimensionally identical externally.

It will and it has. Only did it once though. It made no difference in how the rounds performed, but about ten percent needed more than one primer strike. I started analyzing when I got home and realized I'd grabbed a hundred count of primers out of the wrong box on the shelf.

[willie]

Concerns about regular vs magnum primers have been about accuracy. The literature suggests magnum primers to ignite slow burning powders, which in every instance are loaded in larger charges. In these instances, not using magnum primers can result in more unturned powder kernels. We view this as dirty as it burned dirty. Why? More gunk is left in the bore. With a 900 grain 45 Colt load you will see no increased pressure signs. You might even see improvement. Load'm and shoot'em.