trim case +/=

[MrGee]

Ok the loading manuals give max an a trim to- case lengths measurement.. knowing my chamber dimension an the bullet ogive i will use, i've set up my die for the oal lenght i would like to achieve so as i can limit the bullet jump to rifling... i had a thought about the case it self.. question is would i want it at maximum lenght or minion or yet shorter .. i just picked up a Stoney Point Bullet Comparator .. so i wonder if anyone has any thoughts or experience on it .... any thanks

[kingudaroad]

Here's the skinny on case length by varmint al. I haven't got the tool he reccomends, but I think I need it. http://www.varmintal.com/arelo.htm#Chamber_Length

[Unclenick]

Usually you set the trimmer to trim to minimum plus 0.002" (to allow for case- to-case cutting variations without dropping below minimum). This is done so you can reload and shoot a case until it grows to maximum before you have to spend the time to trim again. Usually 2-4 reloads, depending on whether you are full-length or neck-only sizing.

There used to be a lot of speculative fuss about case length affecting accuracy. It was originally presumed by the pundits that the .222 Remington would always outshoot .223 Remington because the latter had a shorter neck. It just didn't prove to be so, except maybe in some very ticklish bench rest applications. So I wouldn't worry about a few thousandths doing anything you can see on the paper. If the necks are concentric and the chamber is tight enough to keep the bullet co-axial with the bore at ignition, you will be reaching the potential of that aspect of the reloading process.

Nick

Edit:

Well, I was writing while Kingudaroad was posting. I've checked out his link and it is a veritable treasure trove of information. I will modify my above advice to apply as Varmint Al suggests. It will only be true if your chamber neck is matched to your maximum neck space. You can get a chamber reamer made this way, but the Sinclair guage is a good idea. On my Christmas list now, too. Long bullets still may not see a lot of difference in a neck so short the bullet has to jump, but the short ones sure could. 50 mil gap, indeed!