A car travelling at 30 MPH would clear 400 meters in just under 30 seconds. In that time you would have to stop your bike, dismount it, adopt a suitable firing position (at the upper reaches of your range this would probably have to be prone), bring your weapon to bear, adjust for wind direction and bullet drop, (assuming that you are using a .308 this would be negligible but would have to be factored in nonetheless), work out how much to lead the target by, ensure that you are not putting any innocents in the firing line, check variables again, unsafe your weapon and then fire. Add to this the fact that your scope would probably need to re-zeroed what with all of the bumps / vibrations from carrying it on your bike, it would be a very impressive shot Mr Jackal. Hypothetically speaking of course.
Hmmm, apart from the fact that the vehicle would probably be moving away from me so it would be a zero deflection shot and I wouldn't have to worry about drop as at 400m zero the round is only 32cm above sight line at mid trajectory, so aim at centre of mass and it'll get the sucker no matter what. Oh, and I'd be quite happy with a standing shot for a target of that size.
Yes, apart from all that, you don't actually think that I would ride around with a gun slung on my back, do you?
Really
Hmmm, apart from the fact that the vehicle would probably be moving away from me so it would be a zero deflection shot and I wouldn't have to worry about drop as at 400m zero the round is only 32cm above sight line at mid trajectory, so aim at centre of mass and it'll get the sucker no matter what. Oh, and I'd be quite happy with a standing shot for a target of that size.
Yes, apart from all that, you don't actually think that I would ride around with a gun slung on my back, do you?
Really
:-)
And its melons every time.