While I went with the Delta Stryker, the Cronus is essentially the same if you wanted to go that way. Anyway, as I have the same gun as you and went out to a mile with it here is some of my info you may find useful. Happy shooting.
I bought the sphur 4602 for my Tac A1 6.5CM. You can have the sunshade on, or a lens cover, but both will not fit. I was able to dial out to 1300m with this setup.