JimGnitecki
Member
- Joined
- Mar 28, 2010
- Messages
- 1,258
I am running a 357 Mag 158g hard cast RNFP Wolf bullet in both my Cowboy Action Shooting lever rifle and revolvers, that is coming out at a muzzle velocity of about 910 fps from the revolvers and about 1320 fps from the rifle, and is delivering pretty good statistics:
But I was curious about what the ballistic coefficient of this bullet is, because I wonder how far a lever action rifle shooting such a Cowboy Action handload can actually practically shoot in the real world. I wonder: Can it practically be used in moderate range "CAS side matches" if i put a tang aperture sight on it?
Sellier & Bellot published a simplified way to determine the G ballistic coefficient, that does not account for differences in altitude unfortunately (it assumes about 400 meters = about 1300 feet, which is apparently the average elevation for all of Slovakia). But for what it’s worth, that simplified formula is;
G = .0052834 x distance in meters / (square root Vo - Square root Vdistance)
They specify “meters” for the distance, but were silent on the units for velocity, so I had to assume “meters per second” (“m/s” since that is what they use on their ammunition spec webpages), and converted fps to m/s.
The Labradar recorded yesterday’s Vo from the rifle as 1129fps and the V at 50 yards = 45.7 meters as 1053 fps
Plugging in the variables, using m/s versus fps for the velocities (1 fps = .305 m/s), I get:
G = .0052834 x 50*.9144 / (sqrt of 1129*.305 - sort of 1053*.305) = 0.381
This sounds high to me for a flat nosed cast .358” diameter bullet. But I suppose our 3000 foot elevation here around Lethbridge, Alberta, Canada does reduce air resistance versus S&B’s 1300 feet). And I suppose the BC does vary with bullet velocity ranges, and this IS at a pretty slow bullet velocity.
IF this BC is actually reasonable, I could use it to generate a trajectory table.
Does it look reasonable to you, or ?
Jim G
But I was curious about what the ballistic coefficient of this bullet is, because I wonder how far a lever action rifle shooting such a Cowboy Action handload can actually practically shoot in the real world. I wonder: Can it practically be used in moderate range "CAS side matches" if i put a tang aperture sight on it?
Sellier & Bellot published a simplified way to determine the G ballistic coefficient, that does not account for differences in altitude unfortunately (it assumes about 400 meters = about 1300 feet, which is apparently the average elevation for all of Slovakia). But for what it’s worth, that simplified formula is;
G = .0052834 x distance in meters / (square root Vo - Square root Vdistance)
They specify “meters” for the distance, but were silent on the units for velocity, so I had to assume “meters per second” (“m/s” since that is what they use on their ammunition spec webpages), and converted fps to m/s.
The Labradar recorded yesterday’s Vo from the rifle as 1129fps and the V at 50 yards = 45.7 meters as 1053 fps
Plugging in the variables, using m/s versus fps for the velocities (1 fps = .305 m/s), I get:
G = .0052834 x 50*.9144 / (sqrt of 1129*.305 - sort of 1053*.305) = 0.381
This sounds high to me for a flat nosed cast .358” diameter bullet. But I suppose our 3000 foot elevation here around Lethbridge, Alberta, Canada does reduce air resistance versus S&B’s 1300 feet). And I suppose the BC does vary with bullet velocity ranges, and this IS at a pretty slow bullet velocity.
IF this BC is actually reasonable, I could use it to generate a trajectory table.
Does it look reasonable to you, or ?
Jim G