260/Lapua bushing size

Is this a bolt gun or semi? Do you know your dimensions? Take a empty case and seat the bullet of your choice, measure the neck and subtract .002" for a bolt gun, for a semi subtract .003". I use Lapua 260 brass and use 139gr Scenars, loaded is .295" so I use .293" bushings in my bolt guns for a .002" neck tension. This also depends on what size (neck) your reamer was. I had my reamer made with a .298" neck for Lapua brass because the necks are .015". If you don't fire a couple of rounds and measure the neck on the fired case that will be your chamber size, you know what you loaded them to and you need .003" clearance from loaded to a fired case for tactical use, some BR shooters go as small as .0015" clearance and as low as .001" neck tension, but I wouldn't do this for tactical purposes cause unchambering a live round you could have a action full of powder.
Sully