The Iron Sights

[Charles Collins]

I believe that the USMC rifle training, that LHO took part in, would have included some classroom lessons that most likely included a similar diagram to one of the above diagrams. However, I doubt that they would have explained (or even shown) the effects to the trajectory of the slower [Carcano] bullet as I have. So, it seems to me that LHO probably didn’t realize that there was such a significant difference between the bullet trajectories of the M1 that he trained on in the USMC and the Carcano.
Another aspect of the different trajectories (in relation to the scope) occurred to me. If I remember correctly, when the FBI was attempting to zero-in the scope, they used a distance of 100-yards. And we have to also adjust to reflect the ~1.5” height from the center of the bore to the center of the scope (line of sight). Here is a graph showing what the trajectory of the bullet is estimated to be for that situation:




http://www.shooterscalculator.com/ballistic-trajectory-chart.php?t=cb193ad2

Please note that the bullet begins 1.5” below the line of sight, and only needs about 0.5” of height above the line of sight in order to hit a target at 100-yards from the muzzle. Also that the bullet first crosses the line of sight at about 33-yards from the muzzle.

[Charles Collins]

So, when we consider that it appears that LHO first took the photos of Walker’s house and ordered a rifle with a scope shortly thereafter, it can be inferred that LHO probably intended to use the scope to take the shot at Walker. And when we consider that LHO reportedly practiced shooting the rifle in the days leading up to the attempted assassination of Walker, it can be inferred that LHO probably zeroed-in the scope for an eyeballed approximation of the distance of his planned shot. I don’t know the exact distance involved, but it appears to me to be about 105-feet (35-yards). If we assume that LHO estimated the distance correctly, and correctly zeroed the scope to that same distance, then the following chart would give us some useful information.





http://www.shooterscalculator.com/ballistic-trajectory-chart.php?t=2c857f3f


Please note that when the scope is zeroed at 35-yards it is also zeroed at just under 100-yards (where the trajectory crosses the line of sight a second time). And notice how closely this chart resembles the 100-yard zero chart. So, I think that it stands to reason that the issues that the FBI encountered trying to zero the scope at 100-yards should closely apply to the 35-yard zero process that it appears LHO probably attempted.

[Charles Collins]

So, here is some of what Robert Frazier testified regarding the issues that they found with zeroing the scope at 100-yards:

Mr. EISENBERG - Mr. Frazier, could you tell us why, in your opinion, all the shots, virtually all the shots, are grouped high and to the right of the aiming point?
Mr. FRAZIER - Yes, sir. When we attempted to sight in this rifle at Quantico, we found that the elevation adjustment in the telescopic sight was not sufficient to bring the point of impact to the aiming point. In attempting to adjust and sight-in the rifle, every time we changed the adjusting screws to move the crosshairs in the telescopic sight in one direction-it also affected the movement of the impact or the point of impact in the other direction. That is, if we moved the crosshairs in the telescope to the left it would also affect the elevation setting of the telescope. And when we had sighted-in the rifle approximately, we fired several shots and found that the shots were not all landing in the same place, but were gradually moving away from the point of impact. This was apparently due to the construction of the telescope, which apparently did not stabilize itself--that is, the spring mounting in the crosshair ring did not stabilize until we had fired five or six shots.

I submit that it is possible that LHO thought that he had the scope zeroed in at his estimated distance for the shot at Walker. But that since that distance appears to be about 35-yards; and since this also equates to close to the same as zeroing it at 100-yards, that the spring mounting in the crosshairs ring might not have been stabilized yet. And therefore, that when the next shot that LHO apparently took(the one at Walker) the unstable crosshairs ring could have moved. The result being a shot that missed high and to the right and hit the window frame.