I use Dem Bart chequering tools, they have replaceble cutters that are hard as hades & accurately made.
I got a set from F J Wisemans of Birmingham.
The best book i found is "The Checkering & Carving of Gunstocks" author Monty Kennedy it has lots of fine black & white photos & full size patterns to copy or adapt. It is a superb book covering the subject in detail. Have a read & get scratching! Dont start on a fancy piece of walnut rather an old meteor or relum!