I'm vetting my understanding of barrel cant POI shift by explaining it as I understand it publicly 
.
Preface:
cant: rotation about the optical axis
pitch: the angle between the optical & barrel axes formed by a textbook zero (avoids the confusion of using "scope cant")
CCW: counter clockwise
simple kinematics assumed: the bullet exits the barrel w/ an initial velocity & then only experiences gravity
Framework:
POI shifting from cant is a geometry, not physics, problem. Forces on the bullet in the barrel are independent* of cant angle, thus shooting canted is equivalent to shooting w/o cant from a different position. Cant changes the direction of the barrel axis, assuming pitch exists. A geometric description as to why is available. CCW cant depresses the barrel left & CW cant depresses the barrel right.** Distance magnifies the ensuing POI shifts.
Thought Exercise:
A 0 pitch, parallel zero lets one ignore cant's effect over distance. Such a a zero simplifies, but doesn't remove, cant's effect on horizontal displacement.
* barrel sag, the arc of the rifling experiencing the weight of the bullet, etc. are ignored by assuming a uniform barrel
** between 0 & 90 degrees
.Preface:
cant: rotation about the optical axis
pitch: the angle between the optical & barrel axes formed by a textbook zero (avoids the confusion of using "scope cant")
CCW: counter clockwise
simple kinematics assumed: the bullet exits the barrel w/ an initial velocity & then only experiences gravity
Framework:
POI shifting from cant is a geometry, not physics, problem. Forces on the bullet in the barrel are independent* of cant angle, thus shooting canted is equivalent to shooting w/o cant from a different position. Cant changes the direction of the barrel axis, assuming pitch exists. A geometric description as to why is available. CCW cant depresses the barrel left & CW cant depresses the barrel right.** Distance magnifies the ensuing POI shifts.
Thought Exercise:
A 0 pitch, parallel zero lets one ignore cant's effect over distance. Such a a zero simplifies, but doesn't remove, cant's effect on horizontal displacement.
* barrel sag, the arc of the rifling experiencing the weight of the bullet, etc. are ignored by assuming a uniform barrel
** between 0 & 90 degrees
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