Thread: Do you always need to case trim?

Measuring the distance from bolt face to the lands seems to be rather imprecise. Variation from one attempt to another is typically 0.005". Usually it's recommended to repeat measurements several times and average.


Wide ranging discussion. Cleaning rod method is outlined in the 4th post by "Woods"


Shoulder to lands measurement @kimjon shows a home made device. This guy is a DIY mechanical legend (and expert hunter). He got very reproducible measurements with this.


Comparison of "slotted neck" with "home made rod through flash hole" methods.

I trim every firing. I neck turn my cases before the first firing and use Redding bushing dies to get consistent neck tension and low ES. If the cases are not all exactly the same neck length there will be variety between cases, so I trim to just over book max length. Yes, the difference from one case to another is tiny, but it's all about eliminating tiny differences and they all add up. My last load of .300 WM reloads had an ES of 4fps over 5 shots.

I also think it's important to use a good trimmer that supports the case well. I use an LE Wilson jobby.