I don't have a checker myself but, I allways have one or two store bought bullets and what I do is check my scale aginst the wieght of the bullet, if is a 150 grain bullet, my scale should read 150 (this seems to be good enough for me) if it is out alittle no big deal ,I know I won't blow myself up!
by a over charge! If it is accuracy you want I would look to the digital scales they come with checker's and never drift out.