Dick, I think your thoughts are logical on the 'reversal' of drift, between rifle barrels and carbine barrels. (It likely has to be the barrel harmonics of the rifles and carbines used in the 1896-97 testing).

The velocity difference between projectiles fired from rifle and carbine barrels was only around 80 fps.

The gyroscopic twist and direction imparted to the projectiles had to be nearly identical.

I am guessing that later testing and trials gave different results?

The model 1901 rifle sight corrects for drift by angling the eye piece to the Left, as it is moved up the leaf. This would indicate correction for rifle bullet drift being to the Right.

The carbine version of the model 1901 sight has no correction for bullet drift.

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