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Hello all,
I have a 1894 Marlin in .44 Mag and I have a question. I am wondering how to adjust loads for a magnum primer as opposed to standard primer. I was looking up loads with Hodgdon Universal powder and I find myself with lots of magnum primers. I am using 200 RNFP lead bullets. Thanks for any help you can provide.
Email Hodgon then tell us what they say there are a lot of people doing it, but I have not tried it yet I’m the same way with small pistol primers, I have a brick of magnums left.
i use magnum primers with W296, but that's the way i wa taught, plus the load books say to use mag primers with ball powder. now with unversal i don't know, but it should work.
There is no universal "formula" or "rule" for such.
Best way is with a chronograph. Chronograph a 10 shot test string of your load with the standard primers. Drop back 10% on the powder charge (same powder of course) with the magnum primer, work back up in 2/10 gr increments and when the chronographed average velocity of a 10 shot test string is within 10 fps +/- of the load with the standard primer that's it. The powder charge with the magnum primer should be less than with the standard primer....sometimes not by much but still less. If it isn't then redo the test as something is wrong. No guarentee the psi's will be the same but my tests of velocity and psi (yes I measure that) indicate they will also be close.
Using a test string less than 10 shots, particularly a 3 shot test string, can give erroneous results which can be misleading and perhaps dangerous. Use 10 shot test strings.
Larry Gibson
Ive dont it with the 45 acp with excellent results , the load was not max 5.0gr WSL with a 200gr 68 style bullet i just switched to Fed LPM from Fed LP, accuracy was almost identical for 25 shot groups at 25 yards .
About 10 years ago i picked up 25,000 FED LPM primers at a really good price ($14.00 K ) , so far ive used about 20,000 in the 45 acp , whats left im saving for the 44 mag and slow burning powders .
Especially if I was shooting them out of a Marlin, I would adjust nothing.
It sounds like you do not have a load yet with universal? If, that is correct, I would start working up a load as you normally would, by starting out low and working up. And, yes a chronogragh is an essential tool for this load development.
I have had loads, for rifles, where I had a std primer load then work with the same components but with a magnum primer. Sometimes velocity increased, a little, sometime substantialy, some time accuraccy was better other times not. With small amounts you will be using with Universal there is no way of knowing until you try, and try you should. Just beccause it is written to do or not do something doesnt mean it can or cant be done.
Please let us know of your results. thanks
crash87
ball powder yes..
flake or extruded, no (exception H4227)
my general rule, anyway...