Started out with a Rem. 700 LTR 308 20" HB, It's a smaller version of the 700P. I trim every reload to 2.010 keep the head space to .001 Shooting 168 gr.HPBT Sierra bullet over 40.5 gr. of IMR 4064 in a F/C or ADI Case both are thicker the most brass. Win & Rem. brass I would be 1. grain higher on my loads. I agree with 4runnerman on his case prep.
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Case trim .308 Win
- Thread starter 308Loader
- Start date
So I have got into the habit of trimming my .308 brass to 2.005 after each sizing. My question is, should I let them grow to max before trimming?
I trim each time I size the brass. You either must measure each case and sort them out that way, or you just trim. I have a Gracey trimmer for 223, a Giraud trimmer http://www.giraudtool.com/prod02.htm for 30 caliber, and an RCBS Trim Pro for everything else. I can trim cases so quickly with the Gracey and Giraud, basically it is like sticking a pencil in a pencil sharpener, that measuring the stuff would be stupid.
If you are going to be selective about trimming, that is only trim once in a while, you must measure all cases and make no assumptions that just because all the cases you measured are under max, the rest of the cases will also be under max. This is not so in my experience. The odd ball long case pops up.
What affect would it have on the accuracy.
Humans see patterns were none exist. Just search for threads about how Lee Crimp Dies supposedly improve accuracy. They don’t, shooters see improvements where none exist. I have shot mixed trim length brass and my regular trim all brass, some of which is not necessarily trimmed because it was a little short, and I can’t see a difference on paper.
Would longer brass support the bullet better if I'm loading closer to the lands?
What over length case necks will do is cause overpressure conditions. The case neck will be pinched in the throat and you will blow primers. Happened to me decades ago. I just assumed once fired brass did not need trimming. I was wrong, once fired brass lengthens the most of any firing. My recommendation is to trim to minimum and keep that case mouth away from the rifling.
My recommendation is to trim to minimum and keep that case mouth away from the rifling.
I choose to keep the neck of the case out of the throat and the bullet out of the rifling.
F. Guffey
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.
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.
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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.
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
Also wouldn't this increase the case volume a smidge.
I agree.choose to keep the neck of the case out of the throat and the bullet out of the rifling.
F. Guffey
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
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...ure+tool&qpvt=bullet+cannelure+tool&FORM=IGRE