MOA is right, sound advice.
If you still want optics,there are only two scopes to look at, IMO:
The Leupold and the Burris scout scopes.
http://www.midwayusa.com/viewproduct...tnumber=411427
http://www.midwayusa.com/viewproduct...tnumber=606819
If your shooting that well with irons at 100, both of these <3X scopes will have you hitting targets at 500+. Target acquisition is super quick. With the SA factory Brake, you will have no problems staying on target for faster shot cadences.
What ammo you been grouping 1MOA with? I didnt know that rifle was capable of that accuracy out of the box.