He's using Hodgdon's load data for the bullet which uses 3.250" COL in a SAAMI test barrel. How his throat and freebore compare to the SAAMI minimum chamber used in test barrels, I have no idea. How that COL compares to what others use with that bullet, I have no idea, as Nosler doesn't list a recommendation in their databook (at least, not in my copy, which is #6). I can tell you that the seating depth of the bearing surface (so, not counting the boattail) in a case trimmed to 2.484", is 0.411". That's a little more than the usual 1 caliber rule of thumb, but the usual 1 caliber rule of thumb goes over the SAAMI and military maximum of 3.340". At 3.340" the bullet is seated 0.322", and, frankly, that should be enough case grip on the bullet. I just don't know where the throat is with respect to the lands at that point. But I can figure it out.
From Bryan Litz's measurements of this bullet, it is a true tangent ogive bullet with an Rt/R of 1.00. By cheating and using my CAD software to find the contact point on the throat, the bullet will be in contact with the land of a SAAMI minimum chamber when it is seated to 3.2674" COL. So, by seating to 3.250" COL, it is 0.0174" off the lands of Hodgdon's test barrel. That's tight.
green_MTman said:
you want to have your bullet anywhere from .050" to .010 of the rifling for best results
I think it is fair to say a lot of tangent ogive bullets fall into that range, but it's not necessarily so with all bulelts, and certainly not so for secant ogive bullets. From Berger's experiments with secant ogive VLD's:
Berger said:
What has been discovered is that VLD bullets shoot best when loaded to a COAL that puts the bullet in a “sweet spot”. This sweet spot is a band .030 to .040 wide and is located anywhere between jamming the bullets into the lands and .150 jump off the lands.
So, it depends heavily on the gun and bullet. But with the Nosler Ballistic tip, specifically, we have at least one case were it wanted 0.050" off the lands with a 0.224 bullet (for a .308 that is proportional to 0.067" off the lands):
In the Precision Shooting Reloading Guide (Precision Shooting Publications, 1995) Dan Hackett, relates how, in changing bullets for his 40X 220 Swift, he turned his competition seating die's micrometer adjustment the wrong way, and wound up with 20 rounds loaded 0.050" off the lands instead of 0.020" off the lands, as he'd intended. The dogma he had subscribed to at the time said nothing over 0.030" off the lands would shoot best. Faced with pulling down the loads or just shooting them in practice, he opted for the latter. To his amazement, this gun, which had never previously printed a 5-shot group smaller than 3/8” at 100 yds, gave him two ¼” groups and two bugholes in the low ones with these “incorrectly” seated bullets.
MightyMO1911,
In light of the above, you might want to leave your loads where they are. You should be almost 0.050" off the lands with your mistake. It might prove beneficial. The 2% extra pressure doesn't mean much. What everyone calls the SAAMI maximum isn't really a maximum, it's a 10 shot average that allows individual rounds to go as much as 18% over the average without disqualification, so you are going to be will within that in the worst case. I think I would just see what that load does.
