... I had loaded a 130gr. Barnes TSX at 3100 for mine, and for his a 130gr nosler partition also at 3100. Now our target for this shoot was a water jug we placed on the valley floor about 150 yards away, and we were probably shooting at a 30 degree downward angle. These rifles were sighted dead on at 200 yards at the range. Any way shooting down on the target, 50 yards less than the range at which they were sighted for should have you shooting a bit high. Not the case with my TSX I was kicking up dirt in front of the target, but yet my buddies was going over the target like you would suspect. ...
Something is wrong here.
I�m assuming you were shooting a .277� because Nosler doesn�t make a 130g Partition in .308�. That goves us the following BC�s:
.431 Barnes 130g .277� TSX (From Barnes� current web site)
.416 Nosler 130g .277� Partition (From Nosler 5th)
The effective range of a 150-yard target at a 30 degree down angle is 129 yards. (150 yards * cos 30 degrees = 129 yards effective range) We�ll round that to 130 yards.
Zeroed at 200 yards with identical velocities of 3100fps that yields the following trajectories at 130 yards:
+1.42� Barnes 130g
+1.43� Nosler 130g Partition
I suspect there was another unaccounted-for variable. Using a bullet with a lower BC and zeroing at 200 yards causes a HIGHER mid-range trajectory. (Which is why the Nolser Partition is calculated to hit 0.01� higher than the TSX.) If zeroed at 200 yards, and at 3100fps at the muzzle, there is no BC low enough to cause the bullet to drop below line of sight at 129 yards. The lower the BC, the higher the bullet will impact under those conditions. For that matter, there is no BC HIGH enough to hit below line of sight under those conditions, either.
