Obviously I am new to LR shooting. I am about finished with my rifle/caliber selection and today was surfing scopes. I noticed that very few scope come with target turrets, but I see lots of pics on here, and other sites of guys who have them. Are they available aftermarket, or do you have to buy one of the scopes that come so equipped? I cannot imagine that anybody takes off dust caps in the field and uses a screwdriver!