View Single Post
Old August 28, 2012, 04:12 PM   #12
Unclenick
Staff
 
Join Date: March 4, 2005
Location: Ohio
Posts: 21,024
Dan Hackett, writing in the Precision Shooting Reloading Guide tells how he was loading Nosler BT's for his 220 Swift one day, but had 20 rounds loaded before he noticed that in switching from another bullet he'd accidentally turned the micrometer adjustment on his seating die the wrong way. As a result, these 20 rounds wound up seated too deeply, so the bullets chambered 0.050" off the lands instead of 0.020" off the lands as he'd intended and always used before. He considered pulling the bullets, but decided just to go ahead and fire these rounds in practice, and not to expect too much from them. To his astonishment, his rifle, which had never previously grouped 5 shots into under 3/8" at 100 yards, turned in two 1/4" groups and two bugholes in the low 1's with those loads. So much for the "best" distance off the lands being some universal number.

A lot of people may have used those kinds of jumps successfully, but a lot have fooled themselves into never finding their best jump because of believing in them too much. Berger has found their VLD shapes often want to be out as much as 0.150 off the lands to do their best, but it depends on the chamber. With some chambers they actually do best seated 0.010" into the lands (firm contact). You can read their recommended procedure for finding a best seating depth, here.
__________________
Gunsite Orange Hat Family Member
CMP Certified GSM Master Instructor
NRA Certified Rifle Instructor
NRA Benefactor Member and Golden Eagle

Last edited by Unclenick; August 28, 2012 at 04:24 PM.
Unclenick is online now  
 
Page generated in 0.03270 seconds with 8 queries