going to send my bolt of of my CZ550 458 win mag plus "p" to Matrix Gunsmithing have the handle straightened for better grasping but wonder why you would want to fill the end of the bolt knob? Please educate me thanks

I kinda prefer this handle type.

I like it!

Matrix should also have an aftermarket bolt handle that is larger and slightly longer. To me the factory CZ bolt handle looks undersized relative to the action size. AHR offered the replacement bolt handles, so I expect Matrix will have them too.