www.rrarms.com has some great prices.

Go with the Optima for you Colorado gun, TC doesnt recommend full bore projectiles in their rifles.

With the Optima, the thumb hole is a scope only set up but the non thumbhole optima can use open sights.

I use the Truglow ghost ring rear and truglo globe front sight on my Optima. I got tired of yanking sights and scopes every hunting season LOL. Easier just to get another new gun and keep one scoped and the other open sight.