Well I discovered the reason back in '74. I had just got my first Oehler Chronograph for Christmas and in short order I was heading to the range. In NE oregon that year there was 1 - 2 feet of snow at the range (LaGrande Rifle and Pistol Club) and the temperature was hovering around 10 degrees. I had a new M700V in .223 and some loads worked up with Hornady 55 gr SX and Sierra 50 gr Blitz bullets. I was interested in which would be the best load accross the chronograph and for use hunting coyotes in the winter. Several loading manuals speak of using magnum primers with ball powders becuase the deterant on the ball powders make them harder to ignite, particularly in cold weather. I had worked the loads up while living in the milder climate of the Willamette Valley before moving to the harsher climate of NE Oregon. I was using CCI 400 primers and CCI BR primers with H4895, old BLC-2, H335 and BR748. All the loads were 1/2 MOA capable. With the H4895 I would get two or three "click - bangs" out of a five shot string and over 200 fps variation. With the ball powders I not only got the "click - bang" but a horrendus muzzle flash also. Accuracy went to vetrical strings of 2-3 MOA. I went home and bought some CCI 450s, loaded up some more of the same loads and headed back to the range the next day. Conditions were pretty much the same. A loads shot 1/2 to MOA and extreme spread of the shot strings was under 50 fps. In warmer weather (up to 110 degrees) the magnum primers do give better internal ballistics when ball powders are used. It may not show at 100 yards but at 200+ yards the more consistant the load the more accurate.The magnum primers obviously make the difference with ball powders. I have continued to used magnum primers (CCI 450s, WSRs and Federals) with great success in all my .223 loads since that cold wintery day.
Larry Gibson
