Originally Posted by Bruin
Eric Stecker, I am curious as to why the Berger VLD bullet seems to generally shoot best when jammed into the lands while most other bullets generally shoot best when just touching to about 0.030" off the lands. Thanks, Bruin.
The VLD design uses a secant ogive which has an abrupt transition from the bearing surface to the ogive. It seems that this abrupt transition is sensitive to alignement. This has not been proven through controlled testing but the conventional wisdom is that this has an impact on results. If the bullet starts out straight and held straight by the rifling then the bullet is more likely to come out of the muzzle straight resulting in less yaw while the bullet moves from spinning around the axis of the bore to spinning around the axis of the bullet. If the bullet is forced through the barrel with the tip not in line with the axis of the bullet is will produce mcuh greater yaw once the bullet exits the muzzle. This is bad for precision.
There are some folks who are really sharp with math who claim that the amount of yaw that is possible from this situation is too small to make a difference. I am not a math wizard and cannot argue this point. I do know that typically if the VLD does not shoot when jumped (in many rifles it does) then precision can be improved by putting the bullet into the rifling. It seems that alignment is the only thing that is effected when the bullet is successful when jammed.
When neither a jam or a jump produces the accuracy you want there is usually something going on with the barrel. This could be from an uneven throat or throat erosion. The VLDs are sensitive to such things and if everything is square and right you should not have a problems getting them to shoot well. These are the same bullets used by target competition shooters all over the world with excellent results. We do not have a "match" bullet and a "hunting" bullet. They are the same bullet and if they do not work in a given rifle then something is not squared away. This can be challenging to resolve.
Another thing to keep in mind is that our 7mm and 6.5mm bullets are the most streamline VLD we make meaning that they are the most sensitive to such things. We have just finished making some 6.5mm 140 gr (non-VLD) which are meant to be used when the VLDs do not work. It will not be long before we introduce our 7mm (non-VLD) as well. The real trick will be to make sure they perform on game the same way the VLD do. So far the non-VLD have not been tested on game.