Today I saw something truly notable while shooting three very similar loads through a new custom .300 WSM
. While all three loads incorporated the same amount and type of propellant as well as projectiles of very similar design and weight, one of the three produced an initial velocity averaging roughly 150 fps faster than the other two!
The bullets in question here were: a) Sierra's 168-gr Matchking; b) Nosler's 165-gr Ballistic Tip; and c) Lapua's 167-gr Scenar, while the powder charge consisted of 69.0 grains of VV 560.
Of course, great care was taken to insure that the ojive was right at 20-thousandths off the lands in all three instances. Also, the brass was all new (Norma) and the primers were all Federal Gold Match 215M.
Still, the Sierra Matchking and Nosler Ballistic Tip loads both produced mean initial velocities of approx. 3150 fps, while the Lapua Scenar load was moving out at an astounding 3300 fps!!! To my delight, the Lapua load was also the most accurate of the three.
Now, I realize that B.C. and material consistency/density have a not altogether insignificant impact on such things as initial velocity. But gentlemen, I've never known them to account for such extraordinary variations when all other variables are held constant.
By the way, the barrel of the subject rifle is 28" and the ambient temp. in which the shooting was done was around 95 degrees F.
What dost thou think of such a phenomenon, gentlemen?
[ 06-13-2003: Message edited by: Houston Boy ]