Standard vs magum primers. I'm going to find out for myself.

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mmb617

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I've read a lot about the difference between standard and magnum primers and there seems to be no agreement. Some guys say you should download a bit when using magnums while others say the two are pretty much the same and it's not necessary to change your load.

I went to buy some primers today and all they had in SPP and LPP were magnums so I bought them. I'm loading 9mm and .45 acp and have always used standard primers Winchester, CCI and Federal. I see no real difference between the brands I just don't like the way Federals are packaged.

I figured I'll make up some test rounds in both calibers using the magnum primers and chrono them. I'm not near max loads so I'll use the same load as I do with standard primers since I already have chrono data for them. That way I'll have a valid comparison.

I should have my answer to the question in a couple days. Of course that doesn't mean anybody else will agree with what I find, but this is just for my own information anyways.

I'm also curious about the difference between SRP and SPP. Most of what I've read says the rifle primers are harder and some pistols won't ignite them, otherwise they are the same. Which makes me wonder what would happen if I used magnum SPP in my AR? Could this open the door to a slam fire issue?

When supplies are tight as they are now it would be good to know what substitutions can be make safely.
 
I'm also curious about the difference between SRP and SPP. Most of what I've read says the rifle primers are harder and some pistols won't ignite them, otherwise they are the same. Which makes me wonder what would happen if I used magnum SPP in my AR? Could this open the door to a slam fire issue?
Yes, it could, as well as pierced primers, do not use pistol primers in rifle loads. No they are not the same.
 
I believe it's wise to reduce the loads whenever one varies from the published data. Book says standard primer but you choose magnum primers? Err on the side of caution, reduce loads. What's to lose? I started reloading waaaay pre-web and didn't have all the "internet wisdom" and did experiment a lot. Swapped SP for SR primers and in my "warmer" rifle loads using SP primers I got pierced primers. Substituting magnum for stand handgun primers I actually didn't notice much difference mainly because I didn't have a chrony at that time and 98% of my loads were way below max....
 
There can be mechanical and chemical differences between SP, SPM, SR and SRM primers. Depending on the brand, there can be mechanical differences, chemical differences or both.

The mechanical difference is simply a thicker brass cup that better resists piercing at higher pressures. The tradeoff is they must be struck by the firing pin with greater force. This isn't a concern with bolt-action rifles where people do not typically lighten the mainspring to make cocking it easier. It is more likely to be a concern on handguns where a light double-action trigger or an easy-to-rack slide is desirable. Nevertheless, insufficient spring force could be found on any firearm.

The chemical difference is how much powder ignition the priming compound provides. Some heavily-deterred (slow) spherical powders, compressed loads, and loads in very long or very wide brass cartridges require more ignition than other loads to get consistent results.

Remington #1 1/2 primers are standard small pistol primers. #5 1/2 have thicker cups suitable for "magnum" cartridges. Remington does not call them "magnum primers." They contain the same priming compound as the # 1 1/2. I have not pierced them with the hottest 357 loads and I would not expect to. I have found that they ignite very well with full loads of N105 or N110 for example, but not so well with H110, Lil'Gun, or 4227.

I use Fiocchi lead-free "Small Rifle Magnum" primers also. Fiocchi does not retail a non-magnum version. Does their magnum designation simply mean they have a thick cup suitable for higher pressures? Or does the priming compound provide greater ignition? What I know is that my hard-striking (factory mainspring) revolvers, both single and double-action will not reliably fire them. My bolt action rifle has no problem.

To compare the chemical powder ignition force of primers, you might fire primer-only loads with no powder or bullet and use a pressure transducer on the end of the barrel to compare the results. I suppose if you did not have a suitable transducer, you could try a simple ballistic pendulum. You might need a reasonably high speed camera to get an accurate measurement. Nothing exotic, maybe just 120 fps phone camera. The difference between one brand's magnum and non-magnum will either be obvious or not.
 
i have moved over to small pistol mag primers about 20 years ago. my 20 year old test showed a 25 to 50 fps faster over standard primers. now this depends on the caliber, bullet, and powder used. first of this year i ran some tests with winchester standard and mag primers in the 357 mag rifle. 158 hp zero brand bullet and titegroup powder. this load is my match load in nra pistol cartridge silhouette matches. the numbers showed winchester mag primers were about 12 fps faster over winchester standard primers. these test loads were loaded on a dillon 550. so it looks like there is no different between the two.
 
I've done my own informal test, the results were always opposite of what I was expecting...

H335 in the 5.56mm. A Magnum primer is recommended for H335 as it is a ball powder, so I loaded up 2 separate sets of cartridges with the only difference being CCI Mag vs Standard primers. Results: I got slightly higher velocity and better SD with the Standard primers vs the recommended Magnum primers. I did not test for accuracy, and these were not compressed loads. The more I know about burn rate, case volume, and powder density, the more I understand things may change quite dramatically if the load parameters are changed. In my example, if I had 100% case fill, or a compressed load, the Magnum primer may well have provided different results.

I also tested 3 different types of primers with IMR4227 in the .41MAG. Like the OP, I've read 'you must have!' and 'not necessary' for Magnum primers with IMR4227. To that end, I loaded a known charge of 20grn IMR4227 under a Hunter 215grn cast SWC bullet, and fired out of my 20" Marlin 1894, which I figured would magnify any differences in burn characteristics. I loaded 5 each with a standard CCI LP primer, the Winchester Standard/Magnum primer, and a CCI LPM primer. I found, even in the longer burn of the rifle barrel, the standard primer gave the middle velocity reading, but the tightest velocity spread. Winchester gave marginally higher velocity, and a marginally higher SD, the Magnum primer gave lower velocity, and an even bigger velocity spread. Again, if this was a compressed load, or the contrary, a charge at something like 60% case fill... my results may have been very different.

I will be curious to see your results, for sure. But understand, just like published load data, your results are only for that particular load in your particular firearm... change one of the load parameters and anything goes.
 
Comparing regular small pistol primers to magnum small pistol primers, I will say that it depends mainly on the powder used. I've seen huge differences with some powders, and almost no differences with other powders. And the results can vary greatly between different brands of magnum primers.

I saw big differences recently when testing Sport Pistol powder in 45acp. Thread here:
https://www.thehighroad.org/index.php?threads/sport-pistol-powder-in-45acp.860544/
 
Federal primers are the easiest to ignite. Even though I don't like their packaging, it's what I use for all DA revolver loads. I use CCI for all semi-auto loads and for SA (hunting) loads.
 
I will be curious to see your results, for sure. But understand, just like published load data, your results are only for that particular load in your particular firearm... change one of the load parameters and anything goes.

I'm planning on going to the range tomorrow and will let you know what I find out. I do understand that any info I gather means little to anyone else with different loads and firearms. But I'm curious and figure others might be as well.

Here's what I'll be testing:

9 mm 115 gr FMJ over 4.2 gr of titegroup with magnum primers.
That's actually below the listed starting load but I've used it before with standard primers and my guns all cycled without problems and my 4" Compact chronoed an average of 1125 fps.

.45 acp 230 gr FMJ over 6.2 gr CFE Pistol with magnum primers.
This is also a soft load well below max and it's performed well for me in the past with standard primers. It chronoed a lazy 817 fps out of a 4" Compact but never failed to cycle.

.223 with 55 gr FMJ over 23.7 gr of H335 with small pistol magnum primers just because I want to see if that works. I'll only load a couple rounds at a time in the mag just in case I run into a slam fire issue. This is another soft load well below max and has chronoed 2692 fps with standard small rifle primers in my AR.

I generally load everything on the light side as I'm just shooting paper and don't need hot loads. Once I find the minimum that will cycle my guns reliably that's what I stick with. I'm just satisfying my curiosity with this little experiment and don't think I'm doing anything dangerous. I'd just like to know what my options are when I can't always get my preferred primers.

And it's another excuse to get some range time and play with the chrono. I go to the range once or twice a week and like to mix things up a bit to keep it interesting. I'm almost always there by myself so I can putz around all I want without holding anybody else up.
 
I'm planning on going to the range tomorrow and will let you know what I find out. I do understand that any info I gather means little to anyone else with different loads and firearms. But I'm curious and figure others might be as well.

Here's what I'll be testing:

9 mm 115 gr FMJ over 4.2 gr of titegroup with magnum primers.
That's actually below the listed starting load but I've used it before with standard primers and my guns all cycled without problems and my 4" Compact chronoed an average of 1125 fps.

I did a similar test with 9mm, 124gr, and Win 231. I was looking for a new 9mm load, and decided to try the magnum primers I had on hand. Partly out of curiosity, and as a SP option, since they weren't being used for anything else.

I posted my results in this thread for those who helped me out:
https://www.thehighroad.org/index.php?threads/any-favorite-9mm-loads-with-rmr-and-win-231.869674/

For easy comparison with the magnum primers, I copied over the results here:

124gr RNFP, RMR
4.4 gr Win 231, PMC SP
1024
1043
1041
1032
1037
Avg 1035.4
Spread 19
SD 7.64


124gr RNFP, RMR
4.4 gr Win 231, PMC SP Magnum
1050
1048
1036
1048
1048
Avg 1046
Spread 14
SD 5.66


124gr RNFP, RMR
4.4 gr Win 231, Win SP Magnum
1036
1047
1043
1040
1034
Avg 1040
Spread 13
SD 5.24
 
Well I hit the range early today to try and beat the heat which brought up a problem I hadn't thought about. I made a cover that extends beyond my sunshields on the chronograph for these bright sunny days, but today I was early enough that the sunlight was coming in from the side instead of the top. I was able to reposition the cover to the side though and everything worked out.


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I ran a minimum of 30 rounds for each test and didn't see any problems with the magnum primers.

The short version is this:

9mm with 115 gr FMJ and 4.2 gr Titegroup standard primers average 1114 fps, same load magnum primers 1108 fps.

.45 acp with 230 gr FMJ and 6.3 gr CFE standard primers average 823 fps, same load magnum primers 905 fps.

.223 with 55 gr FMJ and 23.7 gr H335 standard primers average 2724 fps, same load magnum pistol primers 2812 fps.

I compared the spent casing and couldn't see any difference. These are standard primers:


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And these are the magnum primers:


50094205518_210f1a3545_c.jpg

50094205503_a8a68dd1a3_c.jpg

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I didn't see anything that would keep me from making these substitutions if I'm unable to get the standard primers for each application.

Am I missing anything obvious?
 
Read a while back that 38 +P cases tend to have less capacity as they are a bit thicker and that this would give you a bit more fps than a comparable 38 case.
That, and mag primers would also get one more fps.

So, loaded up a bunch with mag primers and 3.4g of 700X in a +p case as well as a load with +p case and mag primer using 3.5gr HP38. The mag primer in a +p case got me about 20fps more and the HP38 combo got me a bit over 50fps more over a std case and std primer. So, even the powder selection matters with these experiments. All bullets were 158gr LSWCs. In the end, I may separate +p cases out to keep them in one lot but didn't find it was worth the hassle for that bit of fps.
 
The short version is this:

9mm with 115 gr FMJ and 4.2 gr Titegroup standard primers average 1114 fps, same load magnum primers 1108 fps.

.45 acp with 230 gr FMJ and 6.3 gr CFE standard primers average 823 fps, same load magnum primers 905 fps.

.223 with 55 gr FMJ and 23.7 gr H335 standard primers average 2724 fps, same load magnum pistol primers 2812 fps.
Thanks for sharing that!

I'm not surprised by the results, except for the increased velocity of the 223 rounds with the magnum pistol primers.

Your results in 9mm and 45 follows my suspicion that it depends on the powder, but I wonder if some of the difference in the 45 is due to the lower standard pressure of the 45acp cartridge.
 
Thanks for sharing that!

I'm not surprised by the results, except for the increased velocity of the 223 rounds with the magnum pistol primers.

Your results in 9mm and 45 follows my suspicion that it depends on the powder, but I wonder if some of the difference in the 45 is due to the lower standard pressure of the 45acp cartridge.

I was going to speculate that case fill % and type of powder probably make a big difference when using magnum primers. My 9mm loads filled the case, so it's going to burn back to front no matter what.
 
Just to add even more food for thought to this experiment, the Federal small pistol magnum primers I used with my 9mm loads were called match primers which I'm going to assume means they were held to tighter tolerances for consistency. The CCI standard primers were just that they weren't called match primers. And while the average velocities were almost identical at 1114 and 1108 the deviation from lowest recorded velocity to highest was considerably tighter with the magnum match primers with a spread of 51 fps vs a spread of 97 fps with the standard ones.

As GaryL stated I'm guessing case fill % and powder used plays a part in the results obtained. I'm having fun whether I'm getting any meaningful data or not so maybe I'll play with that a bit. For this test I used Titegroup with the 9mm and CFE with the .45. Perhaps I'll run another round reversing those powders just because I have time on my hands and it's something different to do on my range trips.

When I used Titegroup with the .45 before I wasn't getting the velocities I thought I should and chalked it up to insufficient case fill in the larger .45 cases which is why I switched back to CFE on them. Now I'm wondering how that would change with Titegroup and magnum primers in the .45's. Only one way to find out.
 
My experience was using Sport Pistol in a very light .38spl load. The powder would spread out in all that space and wouldn't ignite reliably. If I pointed pointed the pistol upward and shook it prior to shooting so all the powder was back by the primer it worked okay, but raising the pistol up from a low read position resulted in incomplete burns and low velocity. I then loaded a batch using magnum primers and the problem went away.
 
Federal primers are the easiest to ignite. Even though I don't like their packaging, it's what I use for all DA revolver loads. I use CCI for all semi-auto loads and for SA (hunting) loads.

That's a great idea! I've been using CCI in all my revolvers and have had a few light primer strikes. Each one was always with a S&W while firing DA.
 
Those numbers are significantly different if you ask me . 100 ft./s difference is nothing to ignore in that 5.56 round and that 45 ACP round is nowhere near close to the same either . I’ll also add that you’re using mixed brass which can affect velocity . I don’t see this test as being all that credible .

Maybe you don’t have a problem with your specific loads because they are not at max charges , but no one should conclude based on this test that there is no difference and you can just switch them out regardless of charge or headstamp .
 
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That's a great idea! I've been using CCI in all my revolvers and have had a few light primer strikes. Each one was always with a S&W while firing DA.

Yep. Federal has the easiest to ignite primers. I think all DA shooters who done any "lightening" work on their actions use Federal. It goes for factory ammo, too. Federal brand ammo, like American Eagle, gives the most reliable ignition.
 
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