Q: After 50 years of shooting with .22 Hornets, .270s, .303s, 7mm and 8mm magnums, .300 Weatherby, .300 Win Mag .30-30, .45-70 and two .308s, I am down to a single rifle — a Ruger Varmint in .25-06 — and a five-shot Adler shotgun.
Your article, “Handloading the all-around .25-06” in the April 2016 issue, was interesting historically and the loadings spot on.
You are dead right: it is difficult to get 1036m/s (3400fps) with a 100gn bullet. A charge of 54gn of AR2209 gets 1049m/s (3440fps) in my Ruger’s 65cm (26”) barrel. I may possibly achieve 950m/s (3115fps) for the Hornady 117gn SST with 52gn of RE-19, given a 65cm barrel with 1:10” twist as opposed to your M77 with 600mm (24”) barrel. Is this so?
I have magnum primers left over from my magnum days. How would these primers affect the above loads? Would the hotter primer increase the chamber pressure? Would it burn the slower powder more efficiently?
I did use magnum primers in my .308 with W-748, but as you know W-748 had a special coating.
I bet you haven’t had this question before.
Jeff Grimley
A: I use only standard large rifle primers for reloading the .25-06, even with slow ball powders like WMR and Supreme 780. I don’t see any need for a magnum primer.
Having said that, you can use the hotter primer if you like without any problems. It will have no effect upon erosion, which is caused by hot powder gases having a blow-torch effect on the chamber throat.
The only way to know the velocity of any load in your rifle is to chronograph it. As a rule, though, there’s a gain of about 10-15m/s (30-50fps) for every extra inch of barrel with a magnum.
Ball powders have a heavy deterrent coating which controls the burning rate and it is generally recommended to use a magnum primer with loads of 50 grains or more.
I’m afraid I’ve been asked that question about standard versus magnum primers many times.
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