Normally I load 357 mag cases with 2.7 of bullseye and a 148 gr hbwc with a small pistol primer. Now I have a bunch of 357 mag cases already primed with small magnum pistol primers, what would the effect be on my standard load with the magnum primer instead of a standard primer ? Would it change the load much or will it be safe ?
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magnum small pistol primer ?
- Thread starter rebs
- Start date
100% plus safe. You might see a bit of increased pressure, but not enough to worry about. You might need to tweak the load a bit too.
You don't need magnum primers for .357 Mag loads either. Magnum primers have nothing whatever to do with the cartridge name. They're about the powder used, only.
You don't need magnum primers for .357 Mag loads either. Magnum primers have nothing whatever to do with the cartridge name. They're about the powder used, only.
Hammerhead
New member
Might even have a slight decrease in pressure and velocity from the magnum primer pushing the bullet forward before the powder gets going.
I'm with the others . . . You're not going to even notice the difference.
I once ran out of regular primers (CCI 500) with a similar loading (38 wadcutters), and I just substituted with CCI 550's and never even noticed the difference.
If we were talking a high performance/pressure round, we would be having a different conversation.
I once ran out of regular primers (CCI 500) with a similar loading (38 wadcutters), and I just substituted with CCI 550's and never even noticed the difference.
If we were talking a high performance/pressure round, we would be having a different conversation.
Average Joe
New member
Most likely an increase of about 60 FPS. Nothing that you would even notice.
Loaded 9mm with regular small pistol. Medium load, USPSA minor.
When primers were hard to get, picked up some magnum primers.
Same brass/bullet/powder/OAL.
Magnum loads were an average of 10 fps faster. Yup---ten.
What was interesting is that the extreme spread dropped from
20-25 fps down to under 10. The magnum primers were doing a much
better job of getting the powder lit up!
The only downside of using magnum instead of small pistol is with
small charges/low pressure plinking ammo, you may see some gas
leakage around the primer. Thicker primer cup, low pressure won't
get it sealed 100%. Never had it happen myself.
When primers were hard to get, picked up some magnum primers.
Same brass/bullet/powder/OAL.
Magnum loads were an average of 10 fps faster. Yup---ten.
What was interesting is that the extreme spread dropped from
20-25 fps down to under 10. The magnum primers were doing a much
better job of getting the powder lit up!
The only downside of using magnum instead of small pistol is with
small charges/low pressure plinking ammo, you may see some gas
leakage around the primer. Thicker primer cup, low pressure won't
get it sealed 100%. Never had it happen myself.
Bill, there is also the question of whether the striker or h hammer would work, in some guns, but seriously, that Smith would have no issues. My stupid little .380 won't even function with plain cci. Over the last year, good Lord, I've run into so many petty little problems related to both factory and handloads that I'm at my wits end.
How do you know that magnum primers have thicker cups than standard primers? From what I understand, the only difference between a standard primer and a magnum primer is the brusiance of the burning primer compound.The only downside of using magnum instead of small pistol is with
small charges/low pressure plinking ammo, you may see some gas
leakage around the primer. Thicker primer cup, low pressure won't
get it sealed 100%. Never had it happen myself.
NoSecondBest
New member
Got to love the internet for getting a good answer. The laws of probability say that one of them might be correct. Now to figure out which one...... The most probable one (at least the one I agree with the most) is that it's safe to shoot. Other than that, unless someone actually did some measurement with this scenario, they're just guessing. FWIW, I use magnum primers about 90% of the time and I have for years. I back all my loads off by 10% from what they're called for with standard primers and go from there. I do this so that I only have to keep one primer on hand and I never run out. Also, the cup thickness on handgun primers is the same whether it's a magnum or standard....again from the manufacturer. Those that chronographed some loads and offered some info are on the right track with providing an answer. Lots of answers are simply R&R answers (Read and Regurgitate). R&R answers are the least reliable. If in doubt, go to the source for reliable info.
I load .357 magnum using Alliant 2400 powder also. A few years ago I noticed that Alliant show magnum primers, where previously they showed standard primers. I inquired about the change. The response I received was essentially that that was what they had on the shelf the day they did the testing. Figure .1 to .2 grains of powder going from standard to magnum primers is my thought on the matter.