I have seen in some manuals, that certain loads in standard cartridges , sugjest using magnum primers. It makes sense to me in some cases, If you are using a slow powder in a small bore case, lets say IMR7828, in a 25,06. But I recently saw some loads sugjesting mag primers in a 7mm Mauser with H-414. I would say a mid size case middle bore and a moderate to fast burning powder. Anyway I am going to back the last load I shot with standard primers off by 1.5 grains, ad load 10 rounds each with magnum and standard primers and see what happens. Any experence you might have with similar experaments, would be welcome information,and I will let you know what I learn...t3006

I think you will find that you do not need a magnum primer in standard size cases unless you are using a very slow burning powder.

The example you stated is exactly where I start using magnum primers in my rifles, that is when I use IMR 7828 in my 25-06 with heavy bullets.

Some manuals, especially Speer, recommend the use of magnum primers with all ball powders in virtually any size case. I think this is overkill, that it is not necessary. However, I have a couple of buddies that adhere to this and they are quite happy with the loads they have developed.

Go ahead with your experiment, it will be interesting. You never know what you might find.

I found, for instance, that in my 338 Win Mag I got better velocity, better SD's and better groups when using standard primers with RL 19 than when I used magnum primers. A couple of other 338 Win Mag shooters I know found the same thing.

I guess what this all amounts to is that sometimes you just have to experiment a little.

R F

I work up loads in small to med. cases using std. primers & then I have switched to mags & match to see if my loads get better or worse. It just depends on the powder / bore dia. combo. Give it a try.

I think it was the older Speer manuals that always specified magnum primers for ball powders. I always start out load development with any ball powder using magnum primers.

The Alliant powders specify NOT to use magnum primers with their propellants unless THEY specify. It's note #3 in their handload guide. They generally specify magnum primers for cartridges holding over 80g of powder. With certain powders (H4350 jumps out,) standard deviation on velocity is reduced significantly for anything holding over about 60g powder when I've used magnum primers. My experience has also been better accuracy, higher velocity by just a bit, and lower standard deviation with RL22 when using standard primers versus magnum. Alliant knows what they're talking about when it comes to their powders.

Towards the end of any load development I usually try ALL primers I have on hand to see what, if any, difference they make for both accuracy and velocity. Try it and see but start off using them with lower powder charge.

Well so far
My expeiment showes about a 40 fps increase when using Magnum primers over non. I will load a few more this week, I can't give you my load data cause its way over max for the 7mm Mauser, but the powder is H-414 And i am using 140 grain Balistic tips and 140 grin accubonds, All loads are shooting accuratly through my CZ but the accubond seems to be a little more accurate...tj3006