Case trim .308 Win - Page 2

surveyor · June 20, 2015, 12:33 PM

I trim everytime, mainly for consistiency, and with the trimmer I have it is easier than measuring and checking them.

That said, I set the trimmer to a couple thousandths less than sammi max length, if they need to be trimmed, the are, if they don't, they are'nt.

T. O'Heir · June 20, 2015, 02:12 PM

Trimming after each sizing is totally unnecessary. Checking case length every time is good, but you only trim as required. And that's only when the cases are longer than 2.015".

308Loader · June 20, 2015, 06:12 PM

Original reason for questioning trim length is cannelured bullets. They tend to be short, lots of jump. If the case trim (neck trim) is long .010 longer than, .005 trim, they are .010 closer to lands right? (as measured from cannelured seating depth mark V/S OAL) Still lots of jump, but less than 2.005 trim length.

Also wouldn't this increase the case volume a smidge.

Quote:

choose to keep the neck of the case out of the throat and the bullet out of the rifling.
F. Guffey

I agree.

Lets say I want to be an individual, different, would 2.008 be ok for my 168gr HPBT? No crimp, smidge over .02 off lands as measured by comparator

F. Guffey · June 21, 2015, 11:09 AM

Quote:

Original reason for questioning trim length is cannelured bullets.

308Loader, I do not know of a reloader that allows the cannelur to complicate their reloading. They have simple rules, if the bullet does not have a cannelure do not crimp and if the bullet does have a cannula crimp into the cannula only. Meaning, it is an either or thing/option. When crimping the neck of the case at the cannula off the lands is not an option.

I have a machine that applies cannelures to bullets, it is adjustable, not a problem for me because I do not crimp bottle neck cases. then it goes to case length trimming, crimping requires cases to be trimmed to the same length.

From the old days, it was fashionable to throat 300 Winchester Magnum, moving the bullet out of the case increased case capacity and as we all know the 300 Win Magnum has a short neck. Not a problem, increasing the length of the case with longer necks allowed for more bullet hold. A few reloaders improved on the performance of the 300 Win magnum. I know, then there was that problem of making the case longer and increasing the maximum case overall length.

F. Guffey

Images of bullet cannelure tool. I know, there is a medical term and a reloading term for the meaning of the ring around the bullet for seating and crimping.

http://www.bing.com/images/search?q=...tool&FORM=IGRE

June 20, 2015, 12:33 PM	#26
surveyor Senior Member Join Date: April 13, 2007 Posts: 770	I trim everytime, mainly for consistiency, and with the trimmer I have it is easier than measuring and checking them. That said, I set the trimmer to a couple thousandths less than sammi max length, if they need to be trimmed, the are, if they don't, they are'nt. Last edited by surveyor; June 21, 2015 at 07:17 AM.

June 20, 2015, 02:12 PM	#27
T. O'Heir Senior Member Join Date: February 13, 2002 Location: Canada Posts: 12,453	Trimming after each sizing is totally unnecessary. Checking case length every time is good, but you only trim as required. And that's only when the cases are longer than 2.015". __________________ Spelling and grammar count!