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View Full Version : Substituting magnum primers?



Lester Polfus
10-20-2017, 03:31 PM
So hypothetically speaking, if a guy were to have bought a shit ton of CCI Magnum Large Pistol Primers, instead of regular LPP's, would it be possible to still work up mid-range 10mm practice loads with them without incident?

Asking for a friend...

txdpd
10-20-2017, 03:51 PM
Your friend shouldn't have any problems as long as he starts low and watches for pressure signs, and doesn't try to put large primers into a small primer case.

nate89
10-20-2017, 04:06 PM
Seconded. I have a friend who has shot plenty (ie. over 10k) of 9mm with both small rifle and small pistol magnum primers. Like any other reloading, work up from below maximum and use common sense. I don't know about cup thickness between magnum and standard, but you would also want to verify reliability in igniting the primers, whatever you plan on using, especially if modifications to the mainspring or striker spring have been done for example.

JFK
10-20-2017, 04:10 PM
Should not be an issue if you work up and use good method.

I don't have personal experience with this but there are plenty USPSA shooters that shoot 9mm Major and use magnum or rifle primers.

Lester Polfus
10-20-2017, 04:22 PM
My friend is glad to hear that, although it might have been the tipping point to go out and buy that .44 Magnam I've, I mean, he has been thinking about getting.

Thanks.

olstyn
10-21-2017, 12:19 AM
I've occasionally read of issues with magnum primers not sealing the back of the case as well as normal primers when used for non-magnum loads due to being harder and thus not expanding unless fired at higher (rifle/magnum) pressures. This is reputed to cause accelerated breach face wear via flame cutting. I've never personally had cause to buy magnum primers, so I can't speak to it from personal experience; I'm just passing on what I've read on other forums. Given that max pressure in 10mm isn't much different from 9mm or .40 S&W, I expect any issues that could be caused would be similar.

As far as 9 major shooters using magnum primers goes, that's a whole different ball game. 9mm at 170PF+ is significantly higher pressure than SAAMI max, and thus would be similar to shooting the magnum primers in a magnum load.

busdriver
10-21-2017, 01:07 AM
I've read similar breach face erosion stories. My 9 major load is probably 45k ish psi, and I use rifle primers. No issues at that pressure.

Hambo
10-21-2017, 06:45 AM
Here is what CCI says about magnum primers http://www.cci-ammunition.com/products/primers/primers.aspx?id=29

Mainly it's about ignition/powder selection.

mtnbkr
10-21-2017, 08:17 AM
When I first started loading back in 1998, I bought mag primers and used them for 357mag AND 38special. No issues I could detect...

I have a bunch of SPM primers, but nothing that requires them, so when I run out of SP primers, I'll just use the SPM ones. That's years down the road though.

Chris

Peally
10-21-2017, 08:23 AM
Just load em and shoot.

Jim Watson
10-21-2017, 12:27 PM
9mm Para + 135 gr coated + HP38.
I chronographed with every primer I could lay hands on, SP, SR, SP magnum.
Seven out of eight were the same, within one standard deviation overlap.
Remington 1 1/2 SP standard was a little faster than the magnums and rifles and other SP.

Magnum LP gave somewhat higher velocity in .45 ACP than standard LP but I was shooting powderpuff loads with Bullseye.

1986s4
10-23-2017, 12:49 PM
I've used 'em for years when standard primers are not available with zero issues and no difference noted. Recently I've been trying SR primers in .38 super, minor and major, again zero issues.

TiroFijo
10-23-2017, 03:32 PM
A fex years back, I shot a couple thousand magnum primers (only thing I had at the time) in non magnum handgun calibers, loaded to normal pressures. No issues whatsoever.

Jim Watson
10-23-2017, 04:49 PM
A guy here bought S&B SR for use in 9mm. Misfires are common; apparently they are harder than American SR. But he saved $3 a thousand, so now he has a longterm supply for his seldom shot AR.

Trooper224
10-23-2017, 05:03 PM
He may or may not need magnum primers, depending upon the powder he's using. The use of magnum primers is dictated by the type of powder used, ie. burn rate, not whether or not the cartridge itself is a "magnum" (which many people consider the 10mm to be in all but name. Magnum primers burn longer, not necessarily hotter and are used with slower burning powders in order to achieve a more complete burn. There's a definition of magnum primers that you didn't ask for. ;)

I stopped using magnum primers about two decades back because I found accuracy to be better without them. As for your friend using magnum primers: he shouldn't have a problem since the difference really isn't that great. If the primer sends his load over the red line, he has other issues that need addressing.

deputyG23
10-27-2017, 02:34 PM
I picked up some Winchester small pistol magnum primers in '13 because standards were not available. Used them with WST powder and .38 and 9mm. No issues.

Lester Polfus
10-27-2017, 02:42 PM
Thanks everyone.

This may actually prove interesting. Blue Dot has always given wide standard deviations in velocity. I've theorized that a magnum primer might settle that down a little bit. Guess we'll find out.