I know not everyone can swing it, but you should consider a Nightforce NSX 5.5-22x with a thin reticle like an MOAR-T. They have tons of vertical adjustment in them which is useful if you are reaching out to 1800 yd. They pop up on the EE pretty regularly, you might be able to get one around $2300-2500. Many people will tell you that this is the price of admission for a scope that will perform well in a box test and that you can have confidence in.