Identify each blank and measure its relevant dimensions, including overall length, against the drawing. Inspect the seating end. Pair those with repeated supervised seating observations using the same defined stop and measuring reference, rather than comparing anonymous stick-out numbers.
Keep that particular blank for inspection of its seating end and contact with the defined stop. Include ordinary conforming examples too, so a single awkward end does not become your estimate of normal seating behaviour.
That gives the planned loading study a useful manual baseline. Keep the rejected blank's finding separate; this comparison does not by itself establish the automatic-loading arrangement.