magnum primer question

[kenmulajr]

hey guys, I got some winchester spm primers from a friend who stopped reloading and my question to you is can i use them in my 40 minor load of 180gr berrys fp's over 3.7 of titegroup in my m&p? If so should i drop the powder a little bit to keep them feeling the same( I really like the way it feels)

Thanks in advance,

Ken

[raz-0]

I'm using them because it is all I could find local.

They really make a minimal difference in feel. With something with small charges like TG, I don't know if there's any point to dropping .1 grain as i don't think it'd be a balance in the end.

Since you aren't at the reagged edge, I'd try a few using the same charge first and form an opinion.

[Carlos]

I agree - I would not be concerned about pressure problems with a minor load - particularly in a gun as modern and strong as an M&P. The warnings in reloading manuals are there for "worst case scenarios" like a load on the edge of safe pressure being used in a marginal gun - like an antique pistol. Your gun being .40, is modern as are all .40s.

Magnum primers have been linked (in some cases) to pitting of the breach face over time. Apparently due to failure to seal or some such. Just keep an eye on it. Regards, D.

[larry cazes]

I do use magnum primers sometimes in minor as well as major loads with no problems at all. I drop the charge weight of major loads by 5% and work back up when I switch from standard primers, though. The only times I have ever experienced breachface pitting is when I loaded very fast powders, like clays, to minor PF.

[Guy Neill]

Magnum primers use thicker cups. This means that low pressure loads have a really good chance to allow gases to blow back around the primer cup and erode the breech face. The higher pressure loads magnum primers are intended for will seal the cup against the cartridge case primer pocket and avoid the gases coming back.

Guy

[00bullitt]

I use WSPM primers exclusively in all my pistol loads. I see a better SD and less ES. The most noticeable improvement is how clean the gun is. I use TG. Before I used Magnum primers......I used to get horrible sooting at the feed ramp and end of the barrel and sight area. It almost goes away with the magnums. I see as little as a 10 fps increase in velocity. I have not noticed any pitting of the breechface on my Glocks or Limited guns and I'm going on 20k of these used and just stocked up on another 20k. I have also loaded 40 minor loads to be shot through a Glock with Clays and saw no problems what so ever. I have also shot some W231 and noticed how much cleaner that stuff burned. And before with just standard small pistol.....it was sorta nasty.

I'd have to say just for the pure benefit of how much cleaner the powder burns is worth it to me.

[open17]

I use WSPM in everything. Never had a problem with leakage around them. I suspect that

the combination of fast powder/heavy bullet that is used for most minor loads makes them

seal up in the pocket.

In light charge minor loads I see lower extreme spread with magnum primers, and maybe a

10 FPS increase in velocity. They also ignite 100% in Major 9mm Glocks.

Bill

[larry cazes]

Magnum primers use thicker cups. This means that low pressure loads have a really good chance to allow gases to blow back around the primer cup and erode the breech face. The higher pressure loads magnum primers are intended for will seal the cup against the cartridge case primer pocket and avoid the gases coming back.

Guy

Hmmm.....Was led to believe by folks at winchester that the magnum and standard primers use the same cup thickness and material, just a slightly heavier charge for the magnums. My understanding is that the rifle primers are the only ones with the thicker cup. I have only experienced primer leakage with standard winchester primers and very fast powders, specifically Clays, and minor PF pressures.

Edited April 14, 2008 by larry cazes

[Guy Neill]

That may be true for the Winchester primers. They have some primers that they list for both regular and magnum use. This would suggest they would be somewhat thicker across the board.

My experience is with CCI primers where I know that the magnum primers use thicker cups.

With the CCI primers, the magnum and standard primers also use different priming compounds.

Guy

Hmmm.....Was led to believe by folks at winchester that the magnum and standard primers use the same cup thickness and material, just a slightly heavier charge for the magnums. My understanding is that the rifle primers are the only ones with the thicker cup. I have only experienced primer leakage with standard winchester primers and very fast powders, specifically Clays, and minor PF pressures.

[kmitchl]

I work up a load to the PF and feel I like using whatever primers are in the machine at the time. Once I have settled the other variables, bullet weight, OAL and powder charge, I load enough to chrono and accuracy check with both standard and mag primers. Some loads like the mag primers and some like standard but I have not found any way to predict the outcome. I've also found variations in performance when switching between primer manufacturers.

Keith