I have been using ball powder in my .308 with the standard WLR primer. But I noticed that in a reply to a reader you recommended using magnum primers with charges of ball powder over 50 grains. Should I change over to the hotter cap? If so, what advantage would I gain? Also, should I use a magnum primer in my .300 Win. Mag?
– Kenneth Francis
The magnum primer is a deterrent to difficulties with reduced charges in large cases. It develops more brisance, produces a flash of longer duration with more heat,and is less critical of the position of the powder in the case. If the propellant happens to be toward the forward end of the case or lying along the bottom of it, the magnum primer will still provide more positive ignition. Ball powders along with very slow burning stick powders are almost universally coated with a deterrent which controls their progressive burning characteristics. The hot primer flash ignites them to burn much more positively. Winchester recommends their WLRM primer for use in the .308 with ball powder and in the .300 Win. Mag. with heavy charges of slow burning powders.