Well, if you want suggestions, I think you need to make a jig.

Off the top of my head...

A lever, sprung up at one end against a stop

At the end of the lever, a groove to hold the stock. Cut paralel to the lever pivot.

A second lever, on the same pivot above that, so when you push down it grips the stock against the spring and then forces it down.

Then add a thin angle grinder blade that comes up through the middle of the lever and slices through the stock. The stock being supported on both sides of the cut.

Lift the top lever slightly beyond gripping and the depth stop goes with it so you can eject then advance.

Robin