Re: TVP Team Match Aug 23rd 10:00 a.m.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TCA4570</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: flounderv2</div><div class="ubbcode-body">use JBM for an estimated drop. I know if I shoot a 8" long piece of steel and aim center and hit 1" from bottom, I know what my adjustment is.. And if all else fails, I just remove my pants and shoot again. </div></div>
One inch barrel and 8 inch shot?
For those that may have missed.
Tom has been saying for the last couple shoots that for a true velocity,
we need to shoot 600 and 1000.
Shoot the birds, that's what they are there for.
Adjust velocity in computer to match MOA difference at those ranges.
Good to go for the rest!
Makes more sense to me than getting a speed only 10 feet from the muzzle!
We don't have any targets that close!
</div></div>
The reason Tom is saying this is because IBS matches are at 600 and 1000 therefore by reverse calculating your velocity by the drop at those distances, you then know the velocity of the bullet for that exact distance. Once you know your drop at those distances, does velocity really matter, (not to me). The reason you crono at 10-15 feet is so that you can get the velocity closest to muzzle exit without percussion problems with a crono. You then use that velocity and the Ballistic coeefficient of the bullet and using a ballistics calculator, you can calculate your estimated drop for different ranges. The problem with most manufacturer published BC's is that they generally publish the G1 BC and bullets will actually have different BC's depending on the velocity they are travling. The faster they go, the better the BC and the less drop. As the bullet slows the futher it gets from the rifle, the BC will change and therefore the reason that ballistic calculators are estimates. Now, with that being said, if you use the G7 BC of the bullet for your calculations, you will find that the ballistic calcs that can use G7 will give you a much more accurate calculated drop at further ranges since the calculation when using the G7 BC is not affected as much by the velocity changes a bullet encounters during flight. When using G1 and muzzle velocity as your calc, it has much more of an impact on the esitmated drops as the bullet starts to slow down the further it travels.