CTShooter,
I was drawn to the 6mmBr as were you and a few others here. It has proven to be my most accurate rifle, and of course the most fun to shoot. To date my best shooting has been 1 5/8 at 300 yds. Four of them were 7/8" My goal of 1" at 400 may be over the next hill.
FWIW, I think your observation is very interesting. I never heard of it before.
I'm sure you've heard of barrel whipping and vibration. As I understand it, you tune your load to the physical characteristics of your particular rifle so that the timing of bullet exit coincides with a minimum speed of rifle barrel whip. So that small variations in the exact time of bullet exit do not effect its flight path much because the barrel end is whipping slowly, and therefore has not moved much from the ideal point of exit). a variant of that line of thinking suggests that in addition to the possible up/down left/right whip there is also a radial expansion/contraction that in effect changes bore diameter as it travels up and down the barrel. Again, as I understand it, the ideal bullet exit time coincides with the bore being at maximum constriction. I would guess that this radial expansion, which travels up and down the bore is not perfectly ring shaped, but rather stretches into an ellipse in one direction,lets say vertically for arguments sake) and then shrinks back and stretches in the opposite direction,which would be horizontally in this case). I would then climb way way out on yonder limb and suggest that if this phenomena were occurring at the chamber end of the barrel while the powder burn is still active,it would leave an uneven burn/soot mark on the case. Said mark would extend further down the neck in 2 diametrically opposed places while the spaces in between would show very little mark. Now - if the expanding portion of this distorted radial vibration is at the chamber end, what's going on at the muzzle. Your experience with your small group, and the response/advice of proficient shooters you referenced suggest its an indicator that the constricting portion of the vibration is at or near the muzzle. Its not clear to me why they should be at opposite ends at the same time, I'll ask some people smarter than me to speculate on that. But, if the load,pressure, barrel time, etc) is all in tune with the rifle, maybe that results in the maximum distorted expansion being at the chamber end,allowing uneven blow by) while the max distorted compression being at the muzzle while the bullet is exiting,resulting in highly repeatable bullet path). I think your observation, along with those of some others could lead to some new understanding. I will be looking for this effect as I pursue my goal. Thanks for the post, Hanic
I was drawn to the 6mmBr as were you and a few others here. It has proven to be my most accurate rifle, and of course the most fun to shoot. To date my best shooting has been 1 5/8 at 300 yds. Four of them were 7/8" My goal of 1" at 400 may be over the next hill.
FWIW, I think your observation is very interesting. I never heard of it before.
I'm sure you've heard of barrel whipping and vibration. As I understand it, you tune your load to the physical characteristics of your particular rifle so that the timing of bullet exit coincides with a minimum speed of rifle barrel whip. So that small variations in the exact time of bullet exit do not effect its flight path much because the barrel end is whipping slowly, and therefore has not moved much from the ideal point of exit). a variant of that line of thinking suggests that in addition to the possible up/down left/right whip there is also a radial expansion/contraction that in effect changes bore diameter as it travels up and down the barrel. Again, as I understand it, the ideal bullet exit time coincides with the bore being at maximum constriction. I would guess that this radial expansion, which travels up and down the bore is not perfectly ring shaped, but rather stretches into an ellipse in one direction,lets say vertically for arguments sake) and then shrinks back and stretches in the opposite direction,which would be horizontally in this case). I would then climb way way out on yonder limb and suggest that if this phenomena were occurring at the chamber end of the barrel while the powder burn is still active,it would leave an uneven burn/soot mark on the case. Said mark would extend further down the neck in 2 diametrically opposed places while the spaces in between would show very little mark. Now - if the expanding portion of this distorted radial vibration is at the chamber end, what's going on at the muzzle. Your experience with your small group, and the response/advice of proficient shooters you referenced suggest its an indicator that the constricting portion of the vibration is at or near the muzzle. Its not clear to me why they should be at opposite ends at the same time, I'll ask some people smarter than me to speculate on that. But, if the load,pressure, barrel time, etc) is all in tune with the rifle, maybe that results in the maximum distorted expansion being at the chamber end,allowing uneven blow by) while the max distorted compression being at the muzzle while the bullet is exiting,resulting in highly repeatable bullet path). I think your observation, along with those of some others could lead to some new understanding. I will be looking for this effect as I pursue my goal. Thanks for the post, Hanic
-Al 
