Cartridge Length Tolerances

MassHntr · 12-01-2003, 04:20 PM

All the brass I' m resizing now has been fired once (factory loads). I' ve got a good caliper. How much tolerance is reasonable for cartidge length? These seem to be varying by no more than a millimeter. Thanks.

charlie brown · 12-01-2003, 05:28 PM

The reloading manuals should have min and max case length, and where to trim to. The more uniform the cases the better. Just make sure the cases are within maximum length.

Vapodog · 12-01-2003, 05:57 PM

Most manuals give a case length....and that should be assumed to be a maximum length.

I differ from most reloaders on this so hold your britches here.....

Unless you' re a benchrest shooter, uniformity of case length is only important if you have decided to crimp the bullets to the case. If not, there' s no one that can show me an accuracy improvement in uniformity of case length. It' s purely emotional.

Having said that, I use a Wilson case trimmer that has a method of achieving uniformity of length if you do your job well.

I hate to trim brass, so when I do it, I trim .03 under Max listed in the manuals. This causes me to not have to trim the brass for (probably) the life of the case. Most reloaders try to trim .01 under max length.

It' s up to you, but you must not let the brass exceed the length in your manual. It can cause excess pressures very quickly.......

I can assure you that trimming .03 under the listed length has never caused me a problem.......

Briman · 12-01-2003, 06:48 PM

I just use a le type trimmer- there is not set up involved, you simply trim until it bottoms out, and its really inexpensive. Other than that- what vapodog says- it doesn' t matter much as long as you are not crimping and as long as the lengths are less than the maximum length.

ktscontender · 12-01-2003, 07:23 PM

Triming cases stinks and I avoid it at all costs and I' m pretty much a paper puncher. I' ve gotten to where I only keep 50 or so rounds for each caliber I' m shooting and will trim them all when I notice them creeping towards the max length, I usually go about .003-.005 under max using an RCBS Power trimmer or a Lyman hand trimmer, I like the universal chuck on the Lyman.