Yes, bore diameters differ from manufacture to manufacture. In the muzzlelaoder industry there is nothing like SAAMI to govern and set standards for the industry. In the world of centerfires, were SAAMI has set industry standards, you can count on the bore diameter of your .300 Win mag, 30.06, or .308 Win, being .308 diamter; Your .223 Rem, 22-250 Rem, and 220 Swift being .224 bore dia; and your 7mm-08, 280 Rem. and 7mm Rem Mag, being .284 bore dia.

What loads easy in a Knight, may load hard in a CVA, yet even easier in Traditions, but be a real pain rear to load in a T/C.