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Location: Colorado Springs
Joined: 02/23/2009
Posts: 181
Are These Primers Interchangeable

Can anyone tell me if I can use Small Pistol Magnum primers for a .40 S&W? As you know, there is a shortage of small pistol primers and I can't find them anywhere. Funny thing is, I bought my .40 recently, but before the 'run on guns' created by our current administration. Now, I can find dies, bullets, & powder, but can't find any brass or SPP's Any help on this would be great - I have a couple thousand SPMP's.

Don Fischer's picture
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Location: Antelope, Ore
Joined: 03/24/2005
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if the 40 takes small

if the 40 takes small primer's you can switch. Just be sure to start low and work your way up.

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Location: Colorado Springs
Joined: 02/23/2009
Posts: 181
Thanks Don, I appreciate the

Thanks Don, I appreciate the info.

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Location: Neveda
Joined: 07/22/2008
Posts: 179
A MAG primer is designed to

A MAG primer is designed to burn faster and hotter, by using this you will increase speed and presure,  you will have to start you work-up load from the bottom up and watch for signs of presure.

I would not do this in an auto, wheel gun maybe, break action yes

best of luck with your choice

buffybr's picture
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Location: Montana, USA
Joined: 11/15/2007
Posts: 310
Standard vs magnum primers

NO, magnum and standard primers are not interchangeable straight across.

The pressure inside the cartridge case is created by the combination of the flame from the primer and the burning of the powder. If you increase one (hotter primer), you will have to reduce the other (powder charge) or you will increase the pressure.

As in any new load development, if you change any of the components (including brand of bullets or cases), you should drop your powder charge down 10-20% and work up your new load.

Don Fischer's picture
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Location: Antelope, Ore
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The guys are both right. By

The guys are both right. By going with a hotter primer you will increase pressure so to do it you have to rework your load and re-establish a max load. 

The magnum primer's were developed to ignite large loads of slow powder and what was believed to be hard to ignite ball powder. So if you were using large amount's of powder, ie magnum cases of slow powder, or ball powder supposeably mag primer's were the way to go. I bought a 5# can of H414/W760, same powder. I started out with magnum primer's but ran out and primer's were all but impossible to get. So I switched over to standard primer's and found little difference in proformace. If I were loading for a magnum cartridge of some kind, I would stick to mag primer's, old habit! In a handgun what is determined to be a hard to ignite powder I don't really know. 40 Cal look's very small next to a 338 mag! And the vast majority of my handgun loading is with cast bullet's and fast powder. But without a doubt, they can be changed, just remember the rule and when you go to them, Start load developement all over again. X# of grs of powder behind a mag primer will create more pressure than the same charge of powder with a standard primer. 

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Location: Colorado Springs
Joined: 02/23/2009
Posts: 181
Yeah, the. 40 would look

Yeah, the. 40 would look pretty funny next to the .338!  Thanks to everyone for their inputs.  I'm experienced in reloading and have never had any issues obtaining components.  Unfortunately, Colorado seems to be right smack dab in the middle of the great gun debate currently and this is causing components to NOT be available.  Just a little FYI, my loads are all minimum/starting since I only use these for target shooting.  My hunting/defense loads are put away safe when not in my gun.  It is nice to know I can use mag primers for this purpose.

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