RussB
45 Cal.
- Joined
- Feb 25, 2004
- Messages
- 882
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I guess this belongs under the " for what it's worth " catagory, but I personally find such things interesting.
I have said before, and I will say it again, that energy figures, as computed today by using velocity squared, is practically useless in the real world of hunting with muzzleloaders.
Many of us have a Ballistic Program that we can use for everything EXCEPT our muzzleloaders, simply because we don't know the "exact" B.C. of the round ball we are shooting.
The following may be of some help to those who trying to use a ballistic program to determine Mid-Range trajectory, with different loads. :curse:
In order to calculate the trajectory of a bullet in flight, its ability to push aside the air and retain energy must be known. This property is known as the bullet's Ballistic Coefficient (BC). To calculate an accurate BC for any given bullet requires actually shooting it many times at various velocities, and measuring it's change in velocity over range. There is a simple way to approximate the BC for a roundball, though, so we can play around with theoretical trajectories.
For a roundball traveling more than 1300 fps: (***Note: Sonic, and sub-sonic bullet flight is a totally different subject and does not fit here, so we will begin at speeds over 1300fps.)
B.C. = Ball Wt. in grains divided by (10640 x ball dia. x ball dia.)
Example: For a .535 ball weighing 230 grains, 230 divided by (10640 x .535 x .535) = a BC of .0755. The number 10640 is a constant and never changes. Lyman's Black Powder Handbook gives a BC of .075 for a .535 in. ball, so the agreement is good. :thumbsup:
Older ballistic programs will only accept a three figure entry ie, .0755 vs .075... Don't round up, or round down...simply use the first three figures.
Hope someone finds this helpful. Actually "tracking" a round ball to 200 or 300 yds can be a real eye opener. ::
Russ
I have said before, and I will say it again, that energy figures, as computed today by using velocity squared, is practically useless in the real world of hunting with muzzleloaders.
Many of us have a Ballistic Program that we can use for everything EXCEPT our muzzleloaders, simply because we don't know the "exact" B.C. of the round ball we are shooting.
The following may be of some help to those who trying to use a ballistic program to determine Mid-Range trajectory, with different loads. :curse:
In order to calculate the trajectory of a bullet in flight, its ability to push aside the air and retain energy must be known. This property is known as the bullet's Ballistic Coefficient (BC). To calculate an accurate BC for any given bullet requires actually shooting it many times at various velocities, and measuring it's change in velocity over range. There is a simple way to approximate the BC for a roundball, though, so we can play around with theoretical trajectories.
For a roundball traveling more than 1300 fps: (***Note: Sonic, and sub-sonic bullet flight is a totally different subject and does not fit here, so we will begin at speeds over 1300fps.)
B.C. = Ball Wt. in grains divided by (10640 x ball dia. x ball dia.)
Example: For a .535 ball weighing 230 grains, 230 divided by (10640 x .535 x .535) = a BC of .0755. The number 10640 is a constant and never changes. Lyman's Black Powder Handbook gives a BC of .075 for a .535 in. ball, so the agreement is good. :thumbsup:
Older ballistic programs will only accept a three figure entry ie, .0755 vs .075... Don't round up, or round down...simply use the first three figures.
Hope someone finds this helpful. Actually "tracking" a round ball to 200 or 300 yds can be a real eye opener. ::
Russ
