I'm getting a new barrel for my 7WSM and they said they'd start the lands anywhere I want (they said rather than providing a dimension from bolt face to start of lands, give them a dummy round and tell them if I want it to touch, be a specified distance, etc.) My thoughts are seating a 168gr. berger where it will just fit in the mag. and tell them to make the lands touch. This makes the O.A.L. .018 longer than max and would make a round loaded with a 160gr. Accubond exactly max. (it's .018 shorter from full dia. to tip) if it were touching. My thinking is if the Bergers shoot better with little or no jump, I'm covered and if they want a jump I can set it back. Most posts here and elsewhere are saying .010 to .015 jump is most accurate so has anyone seen best accuracy with no jump? The other question is twist. I was going to get a 1 : 9.5 which is fine according to Berger but I'm tempted to go with a 1 : 9 just to be sure. Suggestions from people with experience with this caliber and bullet would be welcome. Thanks
I run my 7WSM with the 180 VLDs jammed 0.010 into the lands. The rifle is extremely accurate. I use 0.002 neck tension, and can withdraw a loaded round without the bullet pulling out (at least it didn't the 2 times I pulled it out) when I do. I do not make it a practice to withdraw a loaded round from the chamber.
But I have not really tried to jump them. I know some folks that can, but the VLDs generally do not seem to like jumping much. The BTs are different, and the Hybrid will be more like to jump then the VLDs. YOu'll have to shoot some and see.
Yeah I know that isn't much help when setting up a reamer, but it seems to be that each rifle is different.
Interesting, I've had my dummy "measuring rounds", pull out of the case when I use my smallest bushing (over .003 tension) and stuck .003 to .004 into the lands. How much, if any, do you have to reduce your load for the into-the-lands seating as opposed to a jump?
When changing from jumping to jamming, I always start back again with a minimum load and work up. It's the safest way to go.
As for bullets pulling out of the case... It typically occurs when you're miles from home and ready to take down a big trophy and just want to double check to be certain that you have a round chambered.