Magnum primer question

[Black Gun]

Hi, I got a hold of some Federal small pistol magnum primers

My current .40 load is Zero 180gr JHP , 4.9gr N-320 , Wolf spp , 1.170 col , mixed brass .

This gives me a PF of 170 from my STI eagle 5" bushing barrel @ 70*

I would like to know about how much to reduce this load to safely work up a new major load using N-320 or E3 with the magnum primers.

Thanks Donald

[Five of Clubs]

I read a bunch about this on another site. I guess everyone is talking about using these (or whatever you can get) instead of standard SP primers. The theme for the few that knew anything was basically to back off on the powder charge of your normal load and work back up looking for pressure signs. Chrono results did show a small increase in velocity using them (and probably pressure too). I know this is a pretty basic answer and that you probably had already thought about doing this already, but the main idea is that they can be used as long as you do it carefully.

[Black Gun]

I read a bunch about this on another site. I guess everyone is talking about using these (or whatever you can get) instead of standard SP primers. The theme for the few that knew anything was basically to back off on the powder charge of your normal load and work back up looking for pressure signs. Chrono results did show a small increase in velocity using them (and probably pressure too). I know this is a pretty basic answer and that you probably had already thought about doing this already, but the main idea is that they can be used as long as you do it carefully.

'Five of Clubs'

Thanks for the info! Thats about what I was thinking too, do you recall the other sight you were on I would like to read the posts.

Donald

[Five of Clubs]

I read about it on thehighroad.org in the reloading section. IIRC, somebody did chrono tests with small pistol, small pistol magnum, and small rifle primers all with the same load otherwise. It may have been .38 Special. There were several other posts addressing the issue, but one guy actually did the work. Good luck. I'm having more trouble getting powder than primers.

[UW Mitch]

When I switched to Fed Sm Pistol Mag from Fed Sm Pistol regular I picked up a few point in PF. Don't know the correlation to Wolff SPP. Expect a couple points of PF, but nothing big. If you're worried back down the charge just a little, chrono and work back up.

~Mitch

[Black Gun]

When I switched to Fed Sm Pistol Mag from Fed Sm Pistol regular I picked up a few point in PF. Don't know the correlation to Wolff SPP. Expect a couple points of PF, but nothing big. If you're worried back down the charge just a little, chrono and work back up.

~Mitch

Thanks for the info!

[Black Gun]

I read about it on thehighroad.org in the reloading section. IIRC, somebody did chrono tests with small pistol, small pistol magnum, and small rifle primers all with the same load otherwise. It may have been .38 Special. There were several other posts addressing the issue, but one guy actually did the work. Good luck. I'm having more trouble getting powder than primers.

I will check out THR post.

What powder are you looking for?

[michiglock]

Most of what I have read suggest a 5% powder reduction. I have substituted when forced to.

[ap38]

I had to do the same. Backed off a little and it worked out fine.

[Five of Clubs]

I read about it on thehighroad.org in the reloading section. IIRC, somebody did chrono tests with small pistol, small pistol magnum, and small rifle primers all with the same load otherwise. It may have been .38 Special. There were several other posts addressing the issue, but one guy actually did the work. Good luck. I'm having more trouble getting powder than primers.

I will check out THR post.

What powder are you looking for?

I use Unique. I only shoot lead bullets these days and I find it works great, especially in 9mm and .40S&W. There is a little town about 20 miles from me (out in the middle of nowhere) that always seems to have a few primers in stock. I've picked up a brick every two weeks for the last few months and now I have plenty to last out the year. But I can't find Unique anywhere, not even at the massive gun show recently. I did see some Titegroup at a store and I may end up trying that when I am out. Many people like it, I just didn't want to work up a new load if I could avoid it.

[el pres]

I'm in the same boat with the Magnums, thats all I could find. I found

that with my .40 loads they increased the velocity by a mere 10-15 fps..

Edited June 7, 2009 by P.Pres

[RevolverJockey]

I didn't see where anyone mentioned so I will throw it out there. Some Magnum primers are hotter than other, and all primer cups are harder to withstand the assumed pressure increase. If you are on the edge of light striking, this may be all it takes to give you serious headache. Also, some powders react different to Magnum primers - I did some testing with CCI LPM primers in 10mm and gained 200 fps, they were pretty flat at around 250 PF, the boom was also throught the roof. These were same case lot, trinkled on a scale loaded on a T7 with weighed batches of bullets SD ~25 fps. If I had not seen it I would not have believed the primer could make such an impact.

Lee

[Justsomeguy]

Hi, I got a hold of some Federal small pistol magnum primers

My current .40 load is Zero 180gr JHP , 4.9gr N-320 , Wolf spp , 1.170 col , mixed brass .

This gives me a PF of 170 from my STI eagle 5" bushing barrel @ 70*

I would like to know about how much to reduce this load to safely work up a new major load using N-320 or E3 with the magnum primers.

Thanks Donald

Magnum primers are hotter and in small cases then can cause a "double spike" as pressure from the primer alone can fill the case with gas before the powder is lit, pushing the bullet out and lodging it in the lands of the rifling. Then the powder lights up and another pressure wave takes over and pushes the bullet out of the barrel. This is not particularly dangerous but can cause some variance of standard deviation and high/low velocities. This is more prone to happen in a 9mm though. You should be OK with the more medium and slow powders but I wouldn't use magnum primers with fast powders in a .40 as this could light it all up at once and "detonation" could result. 320 SHOULD be ok if you back off from max a bit and try it. Even slower powders would be better as they usually require more pressure to light up anyway.

[Rolex]

justsomeguy- from where did you

find these facts! I would like to check

further on this info, or are these your

personal findings?

Thanks

[open17]

My old 40 minor production load for my G35 was 3.1 N310, 180 gr FMJ,

OAL 1.130 with a WSP primer. PF around 132.

Switched (kind of by accident) to WSPM. Saw an increase in velocity

of 10-15 FPS. Also saw a decrease in the extreme velocity spread,

from 35-40 FPS down to 8-15 FPS. My theory is that the hotter primer

was giving more consistent ignition to the small powder charge.

Since then I use WSPM in everything. 9 minor and major, 40 minor

and major. The WSPM's are a bit harder than the WSP's. If you

have a really light striker spring in your Glock it can be an issue.