Originally Posted by D.ID
IPHY is often referenced in an attempt to draw a distinction between itself and moa but more often than not just adds confusion. Hence my earlier suggestion that you confirm you scope tracks in moa and then forget IPHY.
No, you cannot just 'forget' the number of inches per 100hyds.
Unless your scope adjusts to 1.047 inches per 100yds, it is not MOA.
If it doesn't adjust to 3.6" per 100yds it is not MIL.
You then have however many IPHY your scope actually is.
In all reality, IPHY is the easiest system, and also highest in precision.
Any American could snap right off the top of their head that 1 IPHY is 6" @ 600yds.
We can easily visualize & roughly measure it.
But whatever your adjustments are, it can be entered & used to derive correct clicks, or reticle hold-offs in ballistic software.