VERY easy to use with chairgun, because the mil-dots are always exactly 1 mil apart no matter what magnification you choose. Doesn't matter what magnification your scope is, you can plug your ballistics info into the chairgun 10x or 20x program models and its all still the same on target.
Any time you can take math out of the system -that's a GOOD thing for me! LOL! I used to be big on the bushnell 6-24x mil-dot scopes. They are a true mil at 12x. Get to know where your POI's are in relation to the dots at 12x, and then you have to stick with 12x for all your shooting. Sure you can figure out the dot relations at 6x and 24x, but that's when the math starts... And its a bit of a pain to get 12x calibration going in the chairgun program.... I find it MUCH easier to learn one set of numbers, and enjoy the fact that they stay the same at ALL maginifications with a FFP scope. Simple is better IMO...
I make these up for all my scopes now:
What's great with a FFP mil/mil scope is that this chart is all you need for everything. Its your hold-over at all magnifications, and its your click chart too. If I want to shoot at 80yds, the chart tells me I can hold on dot #3 or click to "3" on my elevation knob. 100yds? -Click to 4.5... Brilliant! Why didn't somebody think of this system sooner! LOL!
NO MORE converting mils to moa: "OK my shot landed 2 mils low, so that's 3.6" per mil at 100yds, but I'm at 50yds so that's 1.something each, and my turrets are 1/4" per click at 100yds so that's how much at 50? I'm confused... Forget it...." -with my old 1/4 moa click scopes... LOL! With a mil/mil scope, your reticle tells you the shot is two mils low, you just click up two and you're done.
I would have FFP mil/mil scopes on just about all my guns if I could. The only draw-back is that on the low end, say 3-5x, the reticle gets REALY small and hard to use. I've found it seems like 6x is about as low as you want to go and still actually get some use out of the mil-dots... So that may be something to consider...
I hope that helps,
Scott in CO