OK, you need to set up with the comparitor to set the distance from ogive to throat. Then you measure the OAL at that setting & load to that OAL when using that bullet.
Try the local car repair place if you're not comfortable drilling & tapping, frequently they'll do little jobs like this for $5.00, or so!
Allan Quatermain: “Automatic rifles. Who in God's name has automatic rifles”?
Elderly Hunter: “That's dashed unsporting. Probably Belgium.”