I just went thru the specs on a lot scopes for a 452 American using medium Talley rings . max objective bell size was 52.8mm/2.077" so most 40mm objective fall in that range but none of the 50mm neither will the A/O models with larger than a 32mm objective , I was looking for a side focus for that reason .
I ruled out the Vortex scope because they all seem to have 1.69" oculars , medium rings max at 38.5mm/1.52" and that depends on the eye piece shape. Weavers , Redfields, Bushnells are the ones that fit these specs .
with high or extra high rings you open up your choices considerably though , then you need to know distances between the adjustment knobs and the bell ends especially with scope bigger than 12X , I went back and settled on the Redfield 4-12x40 , love the circle X recticle on it . fits in the medium rings nice and low, and looks great too.