Let met help you with that. Caliber should be 5.56x45mm, and the next best alternative for the calculator would be .223 remington data.
Bullet weight (or projectile weight) is important. It comes in 55, 62 or 77 grains. At that distance this parameter changes trajectories more than, say, altitude and temperature. Each brand and projectile weight will have different velocities, coefficients and maybe even drag function, but since we don’t know what he used, the most common ammo would be the 55, so I’ll use 55’s data. It’s important for everyone to know that the 62 grains bullet will have a better grouping at that distance than the 55 grains, and the 77 wouldn’t be so big a difference from the 62. This concept of grouping means that, given the caliber, rifle and ammo, even if the weapon remained perfectly still throughout all shots, the bullets would not hit the exact same hole. This is normal, it’s just that the combination of weapon-caliber-ammo can’t achieve a higher precision.The rifles that can achieve much better precision are called sub-MOA rifles, and usually are fed with much better bullets than Crooks must have used. Keep in mind that the usual max distance for Crooks’ combination of rifle-caliber-ammo is around 330-380 yards. Much more than that and the projectile dispersion would be so inadequate for the attempt that a ‘professional’ (to use the forum’s term) wouldn’t consider this if he/she wanted better odds, unless of course such a shooter had to use this combination for other reasons.
All right…
For 55 grains, your coefficient and speed are ok. Usually I use 0.272 and 3260 fps for the ammo I have. If you want to try variations, keep bc between 0.264-0.272 and speed 3050-3260 fps. Drag function: keep it G1 for 5.56x45.
Shooting angle: keep it 0, and I wouldn’t even bother changing it if the angle was less than -+5 degrees. When the shot is fired upwards or downwards at a target, if the angle is higher than 5 degrees, than one would have to compensate for that shot. It wasn’t the case. Even if the 3D modelling comes up with, say 1, 2 or 3 degrees, keep it 0.
Sight height above bore is what it says. Crooks used a 2MOA Holosun holographic red dot from one of the videos I’ve seen, and I would say 2 inches possibly.
ZERO RANGE: you got this one wrong. The zero range is not the distance to target. It is the distance at which the sights of a rifle are configured in such a way that the bullet will hit the exact crosshairs, without using any recticle compensation (and reticle compensation is essentially pointing the gun a little higher or a little lower, using the marks on the scope or red-dot to aim in such a manner that at a different distance than the zero range you can actually hit the target due to the path that bullet makes during trajectory). Zeroing a rifle is going to a range, setting up a paper target at the distance you want to zero that rifle for, firing a few shots, then turning knobs on the scope or red-dot, firing again, until you find that the bullets are hiting exactly the crosshairs. It’s something that Crooks would have done on that visit to the range the day before, for instance. The usual distances for zeroing are 25, 36, 50 and 100 yards. Some people do use 150 and 200 yards.More than that is not common, I would say. You might want to try 5 of these zeros and compare. Try hornady’s ballistic calculator online too.
Distance to show: 190 is ok. 320 if you want to examine other scenarios…
Distance Step: 20 yards
Atmospheric: I would keep it off or maybe 85 F, zero altitude, 29.53, 78%
At that distance and Butler’s altitude I don’t think it would make much difference.
