The biggest gain in loading accurate ammo comes from neck sorting your brass and checking concentricity on your loaded rounds.
If you go back to those Glen Zediker articles you will see that he covers that first.
I agree with MM that deburring flash holes will probably not provide a noticible benefit in accuracy unless you have a precision match rifle.
You mentioned earlier that you have a chrome lined barrel. Chrome lining is done to extend barrel life and many believe that because the chrome plating isn't uniform throughout the bore it has a negative impact on accuracy. I don't have any CL barrels so I can't say from personal experience, however match barrels tend to be stainless steel over other types.
I saw the biggest improvement in the accuracy of my reloads after I started sorting necks and checking concentricity. If the round isn't straight and centered in the chamber, you won't get top accuracy.
Good luck with your efforts. It sounds like you are having fun and that's what counts.
