by noylj on Tue Aug 22, 2017 9:50 am
No, it really makes no difference from what I can see if the bullet is even 0.002" over the nominal size.
I find that 0.356-0.357" jacketed bullets give better accuracy in 9x19 and 9x21 and lead bullets do much better if they are 0.357-0.358".
I always start at the start load and work up and have never seen any problems.
If you don't know the groove diameter of the barrel, any barrel, you are just guessing about what bullet diameter to use.
.223 Rem has a groove diameter specification of 0.224-0.226". If my .223 has a 0.225" groove diameter, I will certainly test 0.225" bullets. SAAMI spec for .223 Rem bullets for use by the industry in ALL guns is 0.2215-0.2245", but I don't load for ALL guns.