Assuming you won't be going much past 100 yards with a .450 Bushmaster, and a 50 yard zero. This one is nice. We got one for my stepson's .223 AR and the illuminated diamond is quick! Plus having 4X available is quite handy.https://swfa.com/swfa-ss-1-4x24-tactical-30mm-riflescope-109309.html
I have the SS 1-6X and love it! Though it has the ability to have exposed turrets, I leave them covered. I learned my holds with a .223 to 500 yards, using the Mil reticle. But I could see it being overkill on a .450 Bushmaster. Your rig, you may want 6X on the top end, I don't know.