To use the culminator; First make sure the correct eye relief is acheived with the C79. Next put the culminator in the bore and (2 person job btw) align the culminator's grid lines so they are parallel/perpinducular to the ranging lines in the sight. Next dial in the site so the tip of the aiming post lines up with I-9 (the little black square in the middle). That's about it. Once the rifle is zero'd on the range, use the culminator again (dont touch the sight) and determine where the aiming post is, ie. G-3 or whatever. so Next time, set your site to G-3 on the culminator and you're perfectly zero'd. Now this is all assuming your C79 isnt the old POS ones like most of the older ones. This, of course, will only work perfectly with a good sight that doesn't lose it's zero... so in other words. Not the C79.