Magnum primer versus regular primers?

[J-Bar]

I don’t have a chronograph to answer this question for myself, so I will appreciate your expertise.

During the primer shortage I was able to get a decent price on some Federal Small Magnum Pistol primers. They worked fine for igniting blackpowder .38 Special loads for cowboy action matches when the regular Federal Small Pistol primers couldn’t be found. Whatever velocity difference there might have been between the magnum and regular primers could not be noticed during competition.

I have been recently loading some of the classic .38 Special target loads, 148 grain wadcutters over 2.7 grains of Bullseye, using the regular Federal Small Pistol primers. I doubt that using up the magnum primers in that load would cause pressure problems (certainly did not see any in the blackpowder loads), but would the magnum primer have any noticeable effect on velocity in that target load? I don’t make any heavy handloads at all. I can use up the magnum primers in the blackpowder cowboy loads so they won’t go to waste.

I’m just curious about how much change in velocity, if any, would the magnum primer contribute?

Thanks for your insight.

 

[Demi-human]

In some cases, , there may be a small increase of velocity. I believe that a maximum load should be worked up to upon a switch to magnum primers, but I don't think the difference between the two would be great when compared to the powder and its variations and ease of overloading.

I recall five or so FPS in my 45Auto. I don't remember the difference when I switched from CCI 400s to 450s, but I did not change the load.

 

[Reeferman]

In 38 special with a Hornady 148 HBWC over 2.8 grains of bullseye I saw between 30 and 40 FPS faster with federal magnum primers over federal standard ones with LabRadar.

 

[J-Bar]

In 38 special with a Hornady 148 HBWC over 2.8 grains of bullseye I saw between 30 and 40 FPS faster with federal magnum primers over federal standard ones with LabRadar.

Thank you, exactly what I wanted to know.

 

[TonyAngel]

Magnum primers usually result in a bit of an increase in pressure and subsequently velocity. If you're at a maximum load and switch to magnum primers, I'd back off a bit and work back up. The big deal about magnum primers is that the cups are a bit tougher and helped to prevent pierced primers with hot loads in race guns using titanium firing/striker pins. The downside is that the cups are tougher so "reading" the primer for signs of over pressure didn't help so much.

 

[Demi-human]

They're already over pressure, they're just trying to get a little bit more.

(Just kidding, don't do that...)

 

[TonyAngel]

Man, should have mentioned, some primers like Winchester large pistol are for magnum or standard loads. Some used small rifle primers for pistol loads. Shooters get creative for all sorts of reasons.

Point is, just proceed with caution.

 

[frankmako]

I have found in my 357 mag rifle load the mag primers give me about 20 fps more.