October 5th, 2020We are often asked: “Can I increase velocity by changing primer types?” The answer is “maybe”. It’s important to understand that changing primer types will affect your load in a variety of ways, including velocity average, velocity variance, accuracy, and pressure. There are too many variables to predict which primer will be better. It will depend on the primer type, the powder, the barrel, and even how your firing pin system is designed. Glen Zediker recommended decreasing your load ONE FULL GRAIN when changing to a different primer type, one that you haven’t used before.Interestingly, however, a shooter on another forum did a test with his .308 Win semi-auto. Using Hodgdon Varget Powder and Sierra 155gr MatchKing bullets (item 2156), he found that Wolf Large Rifle Primers had slightly higher velocities compared to CCI-BR2s. The amount of speed gained by the Wolf primers increased as the charge weight increased, but the middle value showed the greatest speed variance. The shooter noted: “The Wolf primers seemed to be clearly hotter and had about the same, or possibly better ES.” Table:Variety.308 load 45 grains 46 grains 48 grains 48 grains Wolf LR Primers 2750 fps 2810 fps 2883 fps CCI BR2 Primer 2751 fps 2661 fps 27833 fps Speed delta 6 fps 13 fps 16 fps This is a description of one gun, one bullet, and one powder. As they say, Your mileage may vary (YMMV). This illustration shows that you can see significant differences by substituting a component. If you can repeat the chrono run multiple times, a 19 fps increase (with a 46.0 grain powder charge) is significant. A 20 fps increase may result in a better accuracy node, or “sweet spot”, that produces better groups. You have to test it to determine if faster is better for accuracy. WARNING: Be careful when switching primers. It may be tempting to choose a primer that is “faster”, but you must also consider the fact that this choice could produce more pressure. You must therefore carefully monitor pressure signals whenever you change ANY component of a load. Glen Zediker, who died in 2007, recommended that you decrease your load by ONE FULL GRAIN if you are switching to a primer type that you have never used before.Tags:.308 win, CCI BR2, Primers and Pressures, Reloading. Varget. Wolf Primer.
