.308 LAPUA Palma brass

[hounddawg]

Newton's first law states that every object will remain at rest or in uniform motion in a straight line unless compelled to change its state by the action of an external force.

Things like wind reading, trigger control, breathing, and recoil management can only be developed with practice

Best series ever for anyone who wants to learn how to precision shoot at long range

https://precisionrifleblog.com/2015/06/09/how-much-does-it-matter-overall-summary/

 

[reynolds357]

There's a flaw in this reasoning. Groups are never the same extreme spread dimension in inches at all ranges for a given barrel profile. Nor subtend the same angle.

Yep. Well known fact.

 

[Bart B.]

All bullets from the same lot will not have the same ballistic coefficient so even if they leave at the same velocity, they will string vertically. Moreso as range increases.

 

[Unclenick]

As Litz points out, because group spread includes a lateral drift velocity that remains fairly constant (too slow for drag to affect it appreciably during TOF), it has a tendency to be proportional to TOF in a zero wind situation, and more when the air isn't perfectly still. That TOF increases for each successive 100 yards of bullet travel, so the addition to the MOA of the group is proportionally greater at the end of each 100 yards.

 

[308Loader]

wow this thread went sideways all good, it has been an interesting read.

 

[Bart B.]

As Litz points out, because group spread includes a lateral drift velocity that remains fairly constant (too slow for drag to affect it appreciably during TOF), it has a tendency to be proportional to TOF in a zero wind situation, and more when the air isn't perfectly still. That TOF increases for each successive 100 yards of bullet travel, so the addition to the MOA of the group is proportionally greater at the end of each 100 yards.

This is why a given cross wind speed only in the first third of range to a 1000 yard target causes more than 2 times the lateral bullet drift on target than the same cross wind only in the last third.

 

[Unclenick]

Yep! Exactly. You always hear the argument that wind drift should properly be called wind deflection, but the reality is often a mix of the two. In the case of the blue line, you have pure deflection, but for the purple line, you have deflection up to 330 yards, followed by drift due to the lateral velocity already imparted to the bullet by the deflection for the rest of the distance to the target.

Since drag increases with velocity, more drift is imparted by deflection when the bullet is going faster, and that's near the muzzle.