Not tired of the patterns with the Benchmark CastnBlast. I got a IMR pamplet in the mail the other day and it was full of ads for 4007SSC, claiming it was the cat's meow in the varmint cartridges. I figured I'd give it a try. Maybe it will give me those one hole five shot groups I'm after.
I thought you'd like those 50's. The IMR data is showing 3945fps with a charge of 40.2gr out of a 24" barrel. Which is even faster than the Benchmark.