Quote:
Originally Posted by Grizzly Adams
Thanks Pogo, but how do you put a numerical value on all of the above? The formulas for calculating the BC, just gloss over that. I have two Hornady bullets here. Both are .277 dia weigh 150 grains and have very similar shapes, but one has a BC of .525 and the other is .462 The only difference is that form factor.
Grizz
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Lets look at "very similar shape" and Ballistic Coefficient (BC)
270win 150gr bullet @ (we'll use easy number) 3000ft/sec shooting from rifle with 1:10 twist rate.
That means that bullet is traveling 3000ft/sec and spinning once every 10" of travel.When we do the math 12" X speed ÷ twist rate X 60 you'll notice that the bullet is turning 216000 revolutions per minute.(that's what keeps the bullets nose end forward) . That said you don't need much of change in shape to make difference in a drag of said bullet traveling through the air.
Also small difference not just in point of the bullet but base of the bullet makes a difference.
Just looking at the bullet you can't tell much, but send that bullet down the barrel @ 3000ft/sec , that is when even small difference in bullet shape makes the difference in BC.
If you hunt , lets say inside 300yds. don't lose any sleep over BC.
If you shoot 500 to 1000 yards then you might want the bullet with higher BC.