jrs
Member
wrad -
There are no dumb quesitons! But here's a dumb answer or three.
Interior ballistics begins at the breachface and ends at the muzzle.
Exterior ballistics begins at the muzzle and ends at the terminus of the trajectory.
In a match the firing line is the line beyond which no part of the shooters body (or equipment - check the rule book) may extend. Tends to keep everyone behind the danger zone - has next to nothing to do with the distance to the target (from an engineers point of view), and as pointed out by others has very little to do with point of impact at 'normal' ranges.
So to answer your first question put your total station datum on the muzzle (crown) of your rifle at the very last point that will contact the bullet as it exits, which could be a few thousanths before the end of the barrel. Now measure from there to your target the exact distance you desire. Don't forget to allow for Earth curvature which becomes significant at some point.
The bullet follows a curved trajectory BECAUSE of gravity, and the positions of the shooter and target are on a curved surface (actually also because of gravity), so if you don't measure the lineal distance ALONG that curve you'll have the wrong range (distance normal to the Earths surface that the bullet travels to the target) - ie a laser will tell the straight line distance to the target not the distance over which gravity acts. So now for the $64,000 question ... which distance is right? It's very similar to the high angle shot problem where the right answer is the gravity distance to target.
One engineer to another ...
There are no dumb quesitons! But here's a dumb answer or three.
Interior ballistics begins at the breachface and ends at the muzzle.
Exterior ballistics begins at the muzzle and ends at the terminus of the trajectory.
In a match the firing line is the line beyond which no part of the shooters body (or equipment - check the rule book) may extend. Tends to keep everyone behind the danger zone - has next to nothing to do with the distance to the target (from an engineers point of view), and as pointed out by others has very little to do with point of impact at 'normal' ranges.
So to answer your first question put your total station datum on the muzzle (crown) of your rifle at the very last point that will contact the bullet as it exits, which could be a few thousanths before the end of the barrel. Now measure from there to your target the exact distance you desire. Don't forget to allow for Earth curvature which becomes significant at some point.
The bullet follows a curved trajectory BECAUSE of gravity, and the positions of the shooter and target are on a curved surface (actually also because of gravity), so if you don't measure the lineal distance ALONG that curve you'll have the wrong range (distance normal to the Earths surface that the bullet travels to the target) - ie a laser will tell the straight line distance to the target not the distance over which gravity acts. So now for the $64,000 question ... which distance is right? It's very similar to the high angle shot problem where the right answer is the gravity distance to target.
One engineer to another ...