If your reloading for a boltgun start with the bullet ogive 0.010" off the lands and proceed to work up to your max pressure load. Now you have a max load then load 3-5 rounds at that OCL, then 3-5 rounds at 0.005" less OCL and countiue untill you have 3-5 rounds from 0.010" to 0.030" measured from the lands(riflein). Now shoot them and see which OCL gives the best accuracy. Due the same for each powder/bullet combination.

Anytime you subsatut any new component back off the charge and work up to the now new max load. Its the only safe way to do it. Some cartridges and components change little and some have very big changes and you don't know untill you shoot them.

If this is a gun with a tubular magizine like most leveractions you will have to crimp and adjust the powder charge tofind the best accuracy either at or short of the max loading.