HighDesertWolf

I would never seat another type bullet based on the COL of another. because even if the COL from tip to base is the same, its not the tip that contacts the rifiling obviously its where the ogive begins into the full diameter of the bullet and that can vary a ton between two types of bullets especially of different grain weights also COL can vary for different charge weights and powders. I would go about it how jmfa1957 explained it, I deffinately recommend getting the stoney point OAL gauge aswell. In my 308 win load I use a 165 grain Sierra BTHP gameking with a charge of 45 grains varget to stay with in SAAMI specs the maximum overall length for my charge is 2.800 and my minimum is 2.750, I tried seating my bullet so that it would be .030 from the lands and worked it untill I was .010 from the lands. With no difference in accuracy between .030 and .010 but only getting 1.25 inch groups at 100 yards with a rifle that shot .5 inch with remington express 150 grain core lokts I was very frustrated, then I decided to seat my bullets at 2.750 and work up to 2.800 at 2.750 my groups shrunk to .75 inch then I moved up to 2.760 and my groups openned back up to an inch so i backed it off to 2.755 and i was shooting less then .5 inch groups at 100 yards. Basically im trying to say is it isnt always the best to seat your bullets close to the lands. when seating your bullets to the ideal COL what you are doing is timing the bullet just right for the load so that the bullet seats square into the lands though it is very logical to decrease the gap between the lands and the bullet to insure a sqaure fit of the bullet into the bore it doesnt always work.