Home Forums Hunting & Shooting Ask The Gunwriters Magnum primers in standard loads?

My 300 Win Mag target rifle load uses Federal 210 Match, easily lights off ~80gns of H-1000 at sub zero temperatures.

Now that primers are in short supply I took a 0.7 moa @540 yards 5 shot group load and directly substituted Remington 9 1/2 Mag primers that are ~32 years old ( I have several thousand left over from the previous primer shortage).

The 5 shot group is slightly better or at least the same , as conditions will alter the group size somewhat day to day. A sample of one to be sure.

As others have stated , build the load around the primer and other components.

Because of cold weather , Mag primers are used in hunting loads in 30-06 and up.

This thread has been quiet a little while but a few questions come to mind. The shortage in reloading components has pushed me, like many others, to revise loads, use different powders, primers, etc. I found this brisance comparison chart and have some questions:



Few questions - not sure when this data was recorded but the question is whether this has changed over time. Also, I notice the chart includes SD values for brisance - has anyone found whether that corresponds with SD in load velocity or accuracy?

I agree with you a lot of times. However, the example MD gave with groups going from good to bad, or vise versa is because he switched primers on a load with the same charge weight. What he did was change the accuracy node because pressure and velocity changed. Thus affecting barrel harmonics. This is why we work up loads in the first place. To find the load the rifle likes. That is the "hard and fast" rule that everyone here should get, but goes over a lot of guys' heads. If more guys loaded for OCW. I'm hoping guys know wtf that is, they would find handloading and finding accuracy pretty fn easy.

How many samples were used for each SD estimate?

That's a great question and not one I can answer. I've never really bothered to compare primers in the past, always just used CCI and never [over]thought about primer differences in the past. I found the chart to be interesting and wondered if it jives with what others have found over the years, either by directly testing primers or inferred from load velocity or accuracy.

Don't know if you've ever actually read what happened in my experiment in the .220 Swift, but the average muzzle velocity only rose 44 fps between the standard and magnum primers. No doubt the pressure changed--but I doubt the "accuracy node" had much to do with it. I'd experimented considerably with various charges of the same powder and "standard" primers," and the best it would do was a little over 1.5" with the same loads using standard primers.

I also tried varying powder charges after that, but the magnum primer consistently resulted in smaller groups. And the reason I tried the magnum primer was the ballistic lab folks at Western Powders suggested it, since they tended to get more consistent results with magnums as well.

Which is exactly what I've found with various spherical powders in shooting a BUNCH of such "experiments" over the decades. Sometimes primer choice also makes a big difference with extruded powders as well--you might also look up my experiments with 200-grain Nosler Ballistic Tips and Reloder 15 in the .338 Winchester Magnum. But in general they make more difference with spherical rather than extruded powder, because extruded powders tend to ignite easier--though as with anything in reloading there are exceptions.

Thanks MD - I would say your .220 Swift test, finding only 44fps increase between loads with standard/magnum primers answer most of my questions. The chart seems to rank primer brisance roughly as most people seem to report. E.g. WLR quite a bit "hotter" than CCI, Rem, etc. Close to the magnums. The BR primers seem to have SDs on the lower range but sometimes similar to other non-BR primers.

I'm not advocating for the data in this chart but thought it might make for interesting discussion. I can't vett the data in any way and have no idea where it came from originally or who did the testing. I lifted it from here:

Brisance Chart

I use Magnum primers in several different hunting loads. when I've seen a difference to speak of it's been no more than 50 ft per second or so. but it has been mentioned it may change the amount of powder to hit your accuracy mark.

I have been using magnum primers in small cases for years. Pressure testing has shown that with some powders switching from a standard to magnum primer makes no difference. And sometimes makes a large difference. As a kind of loose rule of thumb, ball powders work better with a hotter primer. The older IMR powders, IMR4198, IMR4895, IMR7828, etc, seem to light off just fine with a standard primer. I remember doing some pressure testing on a customers 264 Win mag I built. We were running IMR7828. We started with WLRM, then GM215M, then GM210, then ended with GM155M. Then compared the data. The GM155M worked just as well as the others in every measurable way. And several of these loads were in the 70,000 psi range. And some in the 50,000 psi range.
My testing has shown/proven to me this fact: you wont know until you try.
Charlie

"My testing has shown/proven to me this fact: you wont know until you try."

Exactly....