Shooting with Lyman Sights

[Ithaca Lever]

I've taken this gun to the range a couple of times (Mossberg 144LS) and trying to see what ammo it likes the best and how it shoots on the 50 yd & 100m ranges. The target I was using was a 8" highlighted round target. I found with this gun the Winchester Super X shot the best at 100m with all 10 in the target. I also tried Remington, CCI, and Federal with CCI all shooting lower then the others and even falling off the target. What's the max distance you shooters with these sights will shoot? I just find that size target at 100m for me is my limit. Things start getting blurry