Clockwise verses Anti-clockwise.

[Benelli B76]

The old BSA Standards used to use two springs wound in opposite directions presumably to counter this when bell target shooting. Please correct me if i'm wrong.

To stop them running up inside each other, as I often see when a spring breaks the one part winds into the other as they are the same "thread".

Baz

[TonyL]

From a physics perspective, only pistons that are free to rotate should produce any rotation of the action - otherwise you have not conserved angular momentum.

Yep.

I reported this very effect a few years ago and a few people concurred. The rifle I noticed it with was a Walther LGV. It was a very, very sweet shooting rifle belonging to an ex-HFT champ. High mag scope fitted. Once I had "dialled into it" after a few shots the effect, although slight, was most definitely detectable. Didn't harm the accuracy one bit, mind, and it was also very forgiving.

[RobF]

From a physics perspective, only pistons that are free to rotate should produce any rotation of the action - otherwise you have not conserved angular momentum.

Yep, but you'd be amazed how many think the opposite.