Power Case Trimming

Tools that work and Save Time

- John Barsness

Some shooters believe rifle brass stretches when the neck gets pulled over an expander ball, but experiments with the expander assembly removed have proven this isn’t so. Some shooters also believe brass flows forward during firing, like a glacier, but this doesn’t occur at normal pressures. Instead, handloaded rifle cases “grow” longer because they’re fired in chambers that, by necessity, are slightly larger than the case, and then get resized to fit in the chamber again. When a fired case is full-length sized, the squeezed-down brass has to go somewhere, and the only direction possible is forward.

Eventually brass lengthens enough to require trimming the case mouth; otherwise the mouth gets crimped around the bullet by the front of the chamber, increasing pressures. Many handloaders hate case-trimming, especially handloaders who shoot a lot. My particular downfall is the abundant burrowing rodents living in the West, considered pests by farmers and ranchers, because they gobble up uncountable tons of valuable hay and pasture each year. Some landowners resort to poisoning, but many allow varmint hunters to maintain some sort of balance between rodents and crops.

In Montana we call both Columbian and Richardson’s ground squirrels “gophers.” It’s common to expend 500 rounds in a day of gopher shooting, and prairie dog shooting sometimes involves similar amounts of ammunition. It’s no fun to trim hundreds of cases with a hand-cranked trimmer. I used to do it, back when I had more time than money, but soon learned to wear a glove on my cranking hand to prevent blisters – and still hated the job.