Written by Sierra Bullets Ballistic Technician Gary Prisendorf
Around a year ago I bought a Ruger American Predator rifle chambered in .223 Remington, with the goal of turning it into a coyote extermination machine.
While working up a load for it, I went through all my typical brass prep steps, weighing cases, annealing case necks, uniforming primer pockets and deburring flash holes.
I started wondering just how much difference all my brass prep would really matter for a factory rifle at normal hunting ranges. So I decided to do a little experiment and load up 15 rounds using fully prepped cases and 15 rounds with very minimal brass prep and compare the group sizes at 100 yards.
I weighed out cases until I had 15 within half of a grain of each other, annealed the case necks, uniformed the primer pockets, deburred the flash holes, full length resized, trimmed them to exactly 1.750”, chamfered and deburred the case mouths.
Then I picked out 15 more cases, full length resized them and only checked to be sure that they were shorter than the maximum case length of 1.760”.
I primed all of the cases with CCI #400 small rifle primers, charged them with 24 grains of Alliant Power Pro Varmint and topped them off with a 55 grain Sierra BlitzKing #1455 seated to 2.275” O.A.L.*
So on a beautiful day for February, it reached 60 degrees and very little wind, it was time to burn some powder. From a bench, using sandbags for a rest, I fired 3 five-shot groups with both the prepped and unprepped cases at 100 yards. The results were interesting but not surprising. The best two groups of the day were indeed from the prepped cases, but then again so was the worst group of the day.
Here is how it broke down:
My mixed results did show that the fully prepped cases did average .094” better than the unprepped cases, but the largest group fired from the prepped brass was .012” worse than the largest group fired from the unprepped brass.
In all reality, we can read a million different things into the results. I guess the lesson I learned from this little test is whether I prep my cases or not, I should be able to hit a coyote at 100 yards. I don’t think the coyote will be asking if I prepped my brass or not.
*Disclaimer: Load data represented here may not be safe in your rifle.