A question about magnum vs standard primers.

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SunnySlopes

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I just scored a pound of VihtaVuori 3N37 powder and have a question.

Back in the day, we used magnum primers for slower powders like, Alliant 2400. The hotter primer was to guarantee ignition of all the slower powder before the bullet exited the barrel. Anytime we used 2400, we used magnum primers.

But, for faster powders like Alliant Unique, we used standard primers. Anytime we used Unique, we always used standard primers.

But for the above powder, VihtaVuori 3N37, in some cartridges (357 magnum, for example) they recommend using magnum primers.

In other cartridges, (44 magnum, 45 ACP, and 9mm, for example), they recommend using standard primers.

My question is, if a powder requires a magnum primer, should it not require a magnum primer in all applications? And if a powder can get away with using a standard primer, can it not get away with using a standard primer in all applications?

Or is VihtaVuori just a weird powder?
 
I have always used standard primers with 3N37. It isn't just powder speed that determines the need for a mag primer, and I don't consider 3N37 to be "slow" for a pistol powder, more like medium slow, N-110 is slow. I use standard primers with it as well, shoots great, shoots clean.

Stick pistol powders are less apt to need mag primers than tiny ball powders that pack densely.
 
First, some manuals use one primer for all their loads for a given caliber. For example, they might list a magnum primer for everything in their 357 Mag data, even though many powders they use don't need magnum primers. It's not really a 'recommendation' as much as it is to keep things simple. Speer is one load manual that only recommends magnum primers for specific powders in their handgun data, and they often point that out in their introduction to the data.

So, which source are you using for load data?
 
fxvr5 said:
So, which source are you using for load data?
Click to expand...

For VihtaVuori 3N37 I'm using their website. Not even my 2021 Hodgdon manual lists anything for VihtaVuori.

All other loads/powders I use Speer, Alliant, Lyman, manuals.
 
A good read -
Mysteries And Misconceptions Of The All-Important Primer
https://www.shootingtimes.com/editorial/ammunition_st_mamotaip_200909/100079

Win & Rem only make 1 LP primer. This simplifies it for me. WLP for 45acp & 44 mag. & any other LP.

In small pistol, primer cup thickness is a pressure issue. If pierced primers are seen, (357 mag) go to thicker cup mag primers. I did.

I just use mag primers for every thing in handguns. Even Bullseye powder target loads.

SunnySlopes said:
VihtaVuori 3N37
Click to expand...
The SDS shows no "Nitro" in the powders makeup & is not a ball powder. May work well with a standard primer .

Best to read the primer manufactures primer usage chart.
 
Hornady, Hodgdon and Lyman use magnum primers for all their 357 data. Most of the powders they use don't require magnum primers, but it simplifies things.
 
Walkalong said:
I have always used standard primers with 3N37. It isn't just powder speed that determines the need for a mag primer, and I don't consider 3N37 to be "slow" for a pistol powder, more like medium slow, N-110 is slow. I use standard primers with it as well, shoots great, shoots clean.

Stick pistol powders are less apt to need mag primers than tiny ball powders that pack densely.
Click to expand...

Thanks for your response.

May I ask another question? On the VV website, they show the 3N37 powder loads in 38 special and 357 magnum calibers, using 158 grain copper plated bullets.

For 38 special VV recommends a starting load of 6.5 grains 3N37 for a mv of 991 fps. For 357 magnum they recommend 7.1 grains 3N37 for 1148 fps.

Among my 357 mag revolvers are pythons, pre 27 smith, model 66 no dash and dash 1, 3 screw blackhawk, etc. Older guns no longer manufactured. I load all such loads down to 38 special velocities.

Given VV's load data, would it be feasible to load the 357 according to the 38 special starting load? 6.5 grains vs 7.1 grains? Or should I stick with data for 357?
 
SunnySlopes said:
Anytime we used 2400, we used magnum primers.
Click to expand...

Walkalong said:
Stick pistol powders are less apt to need mag primers than tiny ball powders that pack densely.
Click to expand...

I tried Magnum primers with both 2400 and IMR4227, and got more consistent results with standard primers.... that's just my experience. As Walkalong suggests, it's more the powder composition than what cartridge it goes into, or the powder's relative burn rate. Magnum primers are typically recommended for ball powders, both rifle and pistol, because full and/or compressed charges can be hard to ignite, and particularly in very cold (sub-freezing) temperatures... H335 (rifle) and H110 (pistol) is like this. I did an informal test with H335 in the 5.56mm, using both CCI#400 and #450 primers... I got better numbers with the standard primers than I did with the recommended Magnum primers. Granted, this was with one medium level load in warm temperatures... change any load parameter and things could have changed on paper as well.

Because certain load data suggests one primer or another doesn't mean you can stray, because very likely you can find similar data that uses an alternate. In that case, you would simply reduce and work the load back up carefully to see if your change produces what you are looking for.
 
SunnySlopes said:
Given VV's load data, would it be feasible to load the 357 according to the 38 special starting load? 6.5 grains vs 7.1 grains? Or should I stick with data for 357?
Click to expand...

I don't see why not. Understand, however, that the greater case volume of the .357MAG case will likely produce lower velocity than the same charge in a .38SPC case. Further, and I have no experience with VV powders, if you have a powder that is case position sensitive, the greater void in the .357MAG case can affect good burn characteristics.
 
Charlie98 said:
..........the greater case volume of the .357MAG case will likely produce lower velocity...............
Click to expand...

The loads to which I refer are strictly plinking/informal paper punching loads at ~20 yards. And with my other powders I've been using such minimum levels for years.

But VV is new to me. I'm looking forward to playing with it.
 
I always find it interesting that H110 needs a Small Magnum Pistol primer in 357 Magnum, but igniting nearly twice that in a light 44 Mag Standard Large Pistol primers are sufficient and nearly 3 times the amount of H110 in 450 Bushmaster and standard Small Rifle Primers are sufficient.
 
SunnySlopes said:
Given VV's load data, would it be feasible to load the 357 according to the 38 special starting load? 6.5 grains vs 7.1 grains? Or should I stick with data for 357?
Click to expand...
Yes, you can load the .357 cases using most .38 Spl data. I would, however, be apt to go above staring loads and lean towards the middle range of the data.
 
mcb said:
I always find it interesting that H110 needs a Small Magnum Pistol primer in 357 Magnum, but igniting nearly twice that in a light 44 Mag Standard Large Pistol primers are sufficient and nearly 3 times the amount of H110 in 450 Bushmaster and standard Small Rifle Primers are sufficient.
Click to expand...

Back in the day, before I knew better, I loaded .357 Mag with H110 and standard SP primers and I thought that ammo shot pretty well. To be honest, not much different than what I load now with magnum primers.
 
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