Large Rifle Primers - standard or magnum?

M

Marco Califo

New member
Question is for Bolt guns only. I use Magnum LR or #34 for my auto loaders.
I have and will begin loading for 7mm-08 and 300 WM, in addition to 308.
Q1: 7mm-08, using Stabil 6.5. Use Magnum or regular.
Q2: 300 WM use Magnum when using any ball powder?
Q3: 300 WM use standard with extruded/stick powders?
"Rules of thumb" is what I am fishing for.
I will add that I always use Magnum primers, and often duplex loads when using WC872 experimentally.
 
I use magnum primers for everything. Why? better ignition. But it kinda boils down on which LRP you can find right now. I never could find a difference between the 250s vs the 34s in 30-06.

I did notice better results using a magnum primer in ball powders which you already know. Especially using WC846 in .308 loads . But Def wont hurt using with stick/extruded powder.

Be interesting too see what your results are in testing. But for me I only get magnum primers now.
 
Not that it makes any difference to the primers used, but is ".300WM" the .300 Winchester or Weatherby or something else??

Magnum rifle primers have always been recommended for ball powders and for large powder charges (over 60gr or so) of other powders.


I have never bothered to use them in .308 win, even when using ball powders. Standard primers seemed to light off everything I used in .308 Win just fine.

YMMV
 
I have experimented with magnum primers in non magnum calibers and vice versa. It really comes down to the Individual load. I got better es/sd using cci lr magnums in 308 with tac. My 257wby with reloader 26 did best with winchester LR. They are not all created equal either winchester LR primers are "hotter" than most LR primers and almost equal to a cci magnum. I have a chart somewhere from someone who took the time to scientifically check a large selection of primers and document their findings I'll see of I can dig it up and will post it here. The test was solely for primer brisance and hardness was interesting to see the differences between manufacturers.
 
I have heard of magnum primers being used with standard powders in cold weather hunting conditions to ensure reliable ignition. Generally for use with ball powders. I have found in 223, 308, and 30-06 that standard primers Generally ignite ballnpowders just fine, however the loads can have significantly better sd/es when using magnum primers with the ball powders. And little to no effect with standard powders.

Personally, i would go with all magnum if you can get them. Its so much easier to deal with 1 primers both from keeping them stocked to working up loads .
 
Shadow9mm said:
I have heard of magnum primers being used with standard powders in cold weather hunting conditions to ensure reliable ignition. Generally for use with ball powders. I have found in 223, 308, and 30-06 that standard primers Generally ignite ballnpowders just fine, however the loads can have significantly better sd/es when using magnum primers with the ball powders. And little to no effect with standard powders.

Personally, i would go with all magnum if you can get them. Its so much easier to deal with 1 primers both from keeping them stocked to working up loads .
Click to expand...
A lot of factors must be considered. The three following are most important.
Case volume
Powder type
Load density
 
the real question is what would be the downside of using a magnum vs a standard primer? in any 30 caliber bottle neck cartridge using any type of powder ?

Better ignition is better ignition isnt that what were striving for anyways
 
Reynolds357 has it right. To address the factors he listed:

For large case volumes, use magnum primers. They make more gas than standard primers, and in a large case, even when the case is full, the amount of air space between the grains adds up to make that extra pressurizing gas desirable.

For small case volumes, use standard primers or, in the case of something extremely small with moderate pressure max, like a 22 Hornet, even a pistol primer may be superior. The reason is that extra pressure can unseat a bullet faster than the powder gets going, leading to erratic velocities and barrel times.

Load density. A medium power cartridge like the 30-06 will often do best with a standard primer if the load density is high but better with a magnum primer if the load density is low. The culprit is the same as above; the amount of empty space that has to be pressurized in the case. Low load density makes for a lot of empty space to pressurize and vice-versa.

Powder type. To control progressivity, spherical propellants have deterrent gradient-infused surfaces that make the outside of the grain burn very slowly and then speed up as the surface burns off so to keep making gas faster despite the loss of surface area. Igniting the high deterrent concentration at the surface is particularly hard with earlier deterrent formulations used by older spherical propellants like H335, BL-(C)2, 748, 2520, H380, and H414. Faster burning sphericals, like 231, don't have as high a deterrent concentration at the surface, to begin with, so ignition is less difficult.

In 1989, CCI reformulated their magnum primers to throw hotter sparks and make more gas for higher start pressure to help get the difficult spherical powders lit more consistently. Since then, the metal additives that throw a hot spark shower seem to have been added to most domestic primers, both magnum, and standard.

The bottom line:
No matter whose primers you use, the only way to tell if you should be using the magnum or the standard version is to work up loads with both (assuming you can tell the difference) and then see which one produces a lower velocity standard deviation. That one is almost certainly lighting your powder more consistently. However, as always, it is how the load prints on paper that is the final decider.
 
Another bit of information for what it's worth.

Years ago, when I was trying to determine if using magnum primers in the bitter cold weather would improve performance, I tried large rifle primers and large rifle magnum primers with the same loads with my .30-06 and my .270 Winchester rifles.

I used the same loads in each to be able to see the difference.
Using my Ohler 35P to measure velocity, on a 31-degree day in the middle of winter here in Northern VA, I shot both rifles with both primers and measured the velocity.
Using magnum primers increased velocity by 12 fps on average over 10 rounds with each type of primer.
I didn't see a measurable difference in group size averages.
 
akinswi said:
the real question is what would be the downside of using a magnum vs a standard primer? in any 30 caliber bottle neck cartridge using any type of powder ?

Better ignition is better ignition isnt that what were striving for anyways
Click to expand...
In smaller cases, a magnum primer can cause erratic ignition. The primer pushes the bullet before it ignites the powder.
 
Manufacturers have teams of scientists and decades of experience with reloading; therefore, they have developed safe operating guidelines for their components. Magnum primers in standard cartridges will raise pressure and I'm not willing to risk the possibility of a catastrophic failure.
 
Shadow9mm

I agree, but the group size difference didn't seem to bear that out.
However, that could have been caused by "shooter induced variation" since I was wearing lots of sweaters and a heavy jacket because it was 30 degrees.
Couldn't even be sure where my shoulder was no less where the edge of my shoulder bone was so consistent set up was a guess at best.G

Geauxtide

A 12-fps change in velocity would be equivalent to 0.2 grains of powder charge.
That isn't in the realm of causing catastrophic damage, even if I were loading at Pmax, although I was loading in the middle of the load table where my rifles shoot the most accurately.
At 30 degrees, it doesn't appear to be an issue, but at 90 degrees, I would agree that it might be more or a problem.
 
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