Yep, they work as advertised, but after trying couldn't really find thier need. After you trim, you should be able to fire most brass 3 times, before another trimming. After 4 or 5 shootings, I usually toss anyway. If your one of these guys that likes stretching brass life to 10-12 firings, it would be worth it.

If I start getting bad accuracy, I like to eliminate variables. And neck tension is a varible.