Tommy,
Dual pinned uprade is an extra $55
Go to http://www.whiteoakarmament.com/ and click on complete uppers and you'll see it. I have the option on all my uppers after owning my 1st Bushmaster upper than you had to keep adding windage going back from 300 then 600. With my White Oak pinned uppers the no wind windage zero is the same from 100 to 600 yards and VERY repeatable....
If the $55 is going to crimp the budget skip it and you'll be fine.
If you can swing it definately get it...
George
Oops, sorry for the delay in responding. I think its well worth the $55 as you will not get ANY play in the rear sight after its pinned. It doesnt take much back at 600 to move you so why mess with a rear sight that will have some lash in it if its not pinned? You only do it once, then its done. They just rebarrel the upper ever 3000 or so rounds and you still got your pinned rear sight. For what John charges for his WOA upper, its a no brainer.
John