Need help with core

New guy here. I’m attempting to make my first hornbow. Ive seen tons of videos on YouTube, but what I’m trying to figure out is how does one go about shaping the core without violating the growth rings on the back of the bow? Given shape of the core it looks like one would violate the growth rings. Especially if the rings arent symmetrical with the others. Any advice would be greatly appreciated.

Welcome!

You dont need to worry about violating growth rings at all. Zero.
Everyone tillers their hornbows fom the back so it will evidently happen. Sinew will take care of the tension and wood core will be fine.

Just like Jere said! I use sugar maple planks, sawn to correct dimensions (about 18 x 35 mm), which I plane before bending. Of course you should use good quality plank - decent grain orientation, no knots, cracks or other defects.