Do you always need to case trim?
G'day team,
I've got a question around case trimming I hope for some good discussion around.
I've just got myself a case trimmer and trimmed up my latest batch of .308 brass. I have already loaded this brass and they have been fired twice.
I was told the brass stretches most after the first firing. So basically this 'stretched brass' has already been into my gun and is fine. Even though it was about 3-4 thou longer than the max SAAMI length.
I also load 7mm08 and have the same issue. The brass is longer than max but the loaded cartridge fits inside my weatherby mk 5 ultralight.
However it doesn't fit inside my cousins new tikka t3.
My .308 is a BSA CF2 and I have read that both the weatherby and BSA have quite a generous throat length. Whereas the Tikka is quite short.
So basically, should I be trimming back to Max SAAMI lengths for my brass.
Or do I need to spend more time trimming then working out the correct seating depth to reduce the bullet jump to the lands?
Hope ive got that terminology right. I do have the Nathan Foster book and its awesome but unless I have read it wrong I can't quite understand this bit.
Cheers
Dan
Distance to lands measurement - LINKS
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.