seating depth

[whiter02]

I have been doin some load testing and was wondering when you guys test seating depth how you went about it. How far in the lands and what lengths and how far out and what lengths. I am shooting a 308 with 168 gr. A-max and smk's.

 

[fdshuster]

Starting with a new load and or chambering, I begin with the bullet seated to touch, if groups are what I expect, will stop right there. If I feel the need for improvement will start backing off in .010" increments, never going more than .030" off the lands.

You'll probably find that your 308 will shoot no matter where you seat the bullets.

 

[Shynloco]

You'll probably find that your 308 will shoot no matter where you seat the bullets.

Respectfully, I cannot agree with that statement. I shoot an early 80's .308 (1:10 twist) w/bull barrel that used to shoot incredibly tight groups using Sierra 168 gr HPBT's bullets at the SAAMI spec/Sierra Manual recommendation. In fact, shooting across the counter Federal Match .308 put together simply awesome groups. But the second you got near the jam or within .020 of the lands, the groups would dramatically open up. Even taking Lapua 155 Scenars used by many .308 Palma shooters, if you got into the lands, the groups looked the worst that rifle has shot in over 28 years of using for target shooting. Staying with the "jump" brought back the excellent accuracy and tight groups. It is now time to change out the barrel on that baby so I'll be seeing what this new MG barrel will perform with the jam. I can agree as a "general" and "broad rule," most rifles like the jam. But there are exceptions and that includes .308 as well. So you must test to see how your rifle will react to the jam and remember to back off the powder load some as pressures will increase once you get into the jam.