Working up Loads with Large Rifle Magnum primers

[rhino210]

I acquired some Win Large Rifle Magnum primers (WLRM). Most of the data I can find warns that the magnum primer should not be used in place of a Large Rifle primer due the chance of much higher pressures. However all of the warnings are accompanied by the statement that you can work up a usable load.
Question--Where to start? 10% below the starting load or more? The powder will be IMR 4064 pushing a 165gr Hornady SST in .30-06.

 

[Grumulkin]

I have interchanged large rife with large rifle magnum primers on numerous occasions and in only one case (large rifle magnum in 44 Mag. cases) did I see any signs of a pressure difference. On the down side, in only one case did I see an accuracy advantage with using large rifle magnum primers (in a 357 Herret using IMR 4227). I have never tried plain old large rifle primers in my 375 H&H Mag. and 458 Lott but maybe I should; I have thought, perhaps incorrectly, that a large capacity case needed magnum primers.

In the case of a 30/06, you should be fine starting at the lower end loads and working up from there. I doubt you'll see any signs of pressure or improvement in accuracy with the magnum primers that you wouldn't see with the regular primers.

 

[stovepipe699]

When I tried working up a load in my 30-06 with H 414 powder, Hdy 165 btsp and Rem primers, my best with Mag primers was 1.5'' 5 shot group at 110 yds. When I tried regular primers, my best went down to 5/8'' 5 shot group at 110. Do you have a bunch of Mag primers you want to use up?

 

[rhino210]

Yes, i do have a package and the biggest thing I shoot is a 30-06. Hate for them to go to waste without making a big bang somewhere.

 

[stovepipe699]

I would use them up if the group size is decent. I gave away 800 mag primers and 3 lbs of powder to a neighbor b/c they were part of his pet load recipe. Now I wish I would have kept them for plinker rounds. Oh well.:banghead:

 

[JackOfAllTradesMasterAtNone]

I've interchanged primers before in 30-06. No issues. If you're concerned, then you certainly don't need to start 10% below minimum charge values. Start 1% less than your normal load. Work up, or work a little down to find the accuracy you've already built up.

Think of a magnum primer as a slightly hotter spark plug in your car engine. Not a really big deal. Now, if you had max magnum charges in a large case magnum, then slip in a standard large primer that might not be able to ignite the powder.

-Steve