Punch combo

[gregaquaman]

As a boxer, I guessing your right cross is short because of no shoulder roll. Rolling the shoulder with the punch does 3 things. 1. Contingues the and directing the power of the legs and hips into the punch.2. rolling the shoulder actually adds more reach. 3. with the chin down and shoulder roll your chin is protected from the counter left hook. This is very old school boxing that still works .

Easy way to do this is to turn your knuckles to the floor

[KickPuncher]

I'm not sure if this has been suggested yet, but have you considered working on the timing of your strikes as well? The timing of your moves can be more important than the speed of them. If you pop him with the quick jab, he may reel back or block or move out the way, making the cross you were already sending come short from his recoil. Basically, think less of a fighting game style combo where every hit has to come right after the other quickly or else the combo fails, and more of just continuing your assault with a different move from a different body position.

This is really off-base. OP is asking why he isn't getting extension on his cross. This is a mechanics question, not a strategy question.

All that has been said, especially hip rotation, pivoting the rear foot, and shoulder roll, will extend your reach. Since OP presented the cross-jab question, I generally don't follow up with a cross with a jab unless it's a double jab while circling to set up a new angle/get out of the way.