Thread: Accuracy at 100 vs 600 (example). Variations in accuracy at different ranges

Originally Posted by 243wssm

I spent a little time on the Trentham range some years back, and I believe bullets do 'wake up' and 'go to sleep'.

A chap I was talking to had 3 different 308 loads for his shooting - all with the same cases, powder, and projectiles, with different amounts of powder. I asked why he didn't just use one 'best' load.

He told me that he used different loads so that he could choose when/where on the bullets flight the bullet would hit the second sound barrier. When it hit that the bullet would oscillate around the point of aim, and then settle back onto the central line. So paradoxically he might use a less powerful load when moving back from 600m to 800m - it was all about avoiding the bullet reaching the target while 'awake'.

I thought this a bit odd, but Din Collings confirmed the theory to me, and for me he was an authority to be believed, having won the Ballinger Belt once or twice.

That's my 2 cents worth. Not my theory - someone else's, but that guy was drilling the bull at 800m with open sights, and did it on a regular basis.

Not something I have bothered worrying about given my distances are 200m or less..........

I know that when the bullets "pop through the sound barrier as they drop from super sonic to sub sonic, then the pressure around them induces a wobble and they "re-stabilise" into a steady trajectory afterwards. However the wobble affects their direction of travel and the steady subsonic trajectory may not be where you aimed. Easiest way I can describe this is think of a dinghy with a motor pushing it along. Motor is locked into straight ahead and the water is dead flat boat travels in a straight line. then it hits the wake of another boat (representing the disruption of going trans sonic) and induces a wobble. When the water is flat again the boat steadies into a straight line but now is pointing in a new direction and will continue that way.

For the situation above I can think of a few reasons for the different loads that are not "tuning" per se. To push the speed up high enough that that it stays above super sonic speeds at longer ranges uses more powder and more recoil. For example, to get 200fps increase at the muzzle (which pushes the drop through the sound barrier another 150yds out) on my 303 with a 175gr pill takes it from a minimum ADI load to just over maximum recommended load. (43gr 2209 increases to 48, or 38gr up to 43gr of 2208)

I dont need the extra velocity so I use a medium load.