Small pistol magnum primers in a 9MM?

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TwoEyedJack

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I was reloading 9MM last night and ran out of small pistol primers. I have a thousand small pistol magnum primers from CCI, no. 550.

Has anyone tried using magnum primers in a 9MM? This load features 5.0 gr. Bullseye under a 115 gr. Winchester JHP (5.1 gr. is listed as max in my Hornday manual). The firearm in question is a Ruger P89, which I don't think you could blow up if you wanted to. Would it be safe to use magnum primers in this load?

Thanks!
 
They are safe to use if you start over from scratch and work up your load. I would stop a tenth or two from max, or sooner, if the recoil, velocity, or brass ejection seemed to be too much.
 
I'm with Walkalong on this, work back up and watch for pressure signs. I don't know what the F.P. spring tension is like on those P89's, but I think the primer cup is slightly thicker on the CCI-550's, but maybe not?
 
Smitty, I have noticed that the Alliant data shows lower maximums. I have been shooting this load since about 1989 (I got one for the first P89s) using the Hornady book. Thousands of rounds without even loose primer pockets. Some of my brass has been reloaded 6 or 7 times. Makes you wonder if Alliant is publishing CYA recipes instead of safe maximums.

Anyway, I think I will dial the load back a half a grain and check for pressure. Or maybe not mess with it and use the mag primers in my .357 M66, which only gets mid-range loads anyway and is no where near max.
 
TwoEyedJack said:
Smitty, I have noticed that the Alliant data shows lower maximums.
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Alliant shows data for a bullet of different construction. The Gold Dot is technically a plated bullet and the copper vs. gilding metal jacket, not to mention a different seating depth can easily account for pressure differences between the Alliant and Hornady data.
 
Anyway, I think I will dial the load back a half a grain and check for pressure.
Click to expand...

I don't have a problem using magnum primers in place of standard primers in anything, but the rule of thumb is to back off maybe 5% if you're using max loads with standard primers just to start, that's why I recommended the Alliant max load. Likely you can move back towards your original charge if it shoots ok.
We try to encourage a safe approach for the benefit of all, because you never know.


NCsmitty
 
When using Winchester brass, primers, Rem 115gr JHP, and Unique powder, I had to reduce the load from 5.8 grains to 4.8 grains (approx. 17%) to get the same muzzle velocity when changing from standard WSP to magnum WSP.
 
Even though magnum primers make only a small difference in pressures you should always rework your load when changing components. Like said above, drop back and work up your load again. If you have a Chrono check your current velocity and stop adding powder to the new load when you achieve the same velocity.
 
Are there any published load books out there that give data using magnum primers, for applications where one doesn't traditionally use magnum primers? I wouldn't mind using almost 20% less powder to get the same velocity (especially when magnum primers are often the same price or cheaper), but I like to work within the ranges defined by one or more reputable, published load books.
 
You don't typically find published load data using magnum primers in non-magnum cartridges. Can't fault the manufacturers and publishers for their desire to avoid law suits.
 
You don't typically see load data using magnum primers in applications where they are not needed because they can lead to premature high pressures before velocity gets up to where it could be with a normal primer. This is true even in magnum cartridges depending on powder (2400 comes to mind).
 
If you blow up your 9mm sue to magnum primers, your load is way past the safe limit to begin with, or you are using Clays under a 147gr bullet.
 
BeerSleeper said:
I wouldn't mind using almost 20% less powder to get the same velocity (especially when magnum primers are often the same price or cheaper), but I like to work within the ranges defined by one or more reputable, published load books.
Click to expand...
There's no way you will save 20% of your powder with a magnum primer. You will be lucky to use 2% less and that's on a good day! Really...
 
ArchangelCD said:
There's no way you will save 20% of your powder with a magnum primer. You will be lucky to use 2% less and that's on a good day! Really...
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I haven't tested, so I don't know.

Post 11 reported achieving the same velocity with 4.8 gr vs 5.8 (17% less). I called it 20 for a round figure...
 
Assuming the same bullet and same OAL, I find it hard to believe that a mag small pistol primer gave the same velocity with 4.8 Grs of powder vs 5.8 Grs of the same powder using a standard primer.

Perhaps some tests are in order.
 
Last shooting over a chrony I did w/ WSP & WSPM in 9mm showed about +20fps or so using same charge of HS6. I didn't see much velocity difference, but I guess other, faster powders could react differently.
 
Walkalong said:
Assuming the same bullet and same OAL, I find it hard to believe that a mag small pistol primer gave the same velocity with 4.8 Grs of powder vs 5.8 Grs of the same powder using a standard primer.

Perhaps some tests are in order.
Click to expand...
Ain't that the truth...

I have a VERY strong feeling that if using a magnum primer would save 20%+ on powder there would be a lot of reloaders using magnum primers considering they cost no more than standard primers. I know a lot of reloaders and most are "frugal" and would jump at the chance of dropping the reloading costs by 20%... That is one of the reasons I highly doubt it's possible. (and my own tests with a chrono)
 
When in doubt I find I rarely go too far astray by following the directions - lol - all of my load data for my four calibers was developed using standard small and large pistol primers, so that is all I ever use. Unless there were some zombie attack emergency situation that required using magnum primers, I would try to trade them to a fellow reloader who could use them.
 
jcwit said:
Do you REALLY believe this?

Why are you loading to the max or even over it? Does the target care?
Click to expand...
When the P89 came out, there was an article published in either Guns and Ammo or Shooting Times, where they subjected this gun to some pretty strenuous testing. The first was that they threaded the barrel and installed a stainless steel plug within 1/10" of the nose of a NATO proof round. The gun was fired remotely. It blew out the extractor. After replacing the extractor, they put in a new barrel and fired 5,000 rounds through it without incident. The next test was to mill away all the slide material under the ejection port. The gun was fired 5,000 rounds without incident. It is definitely an over built 9MM.

I never really saw any utility in down loads for a cartridge that is pretty weak to begin with. Still don't.
 
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