BL
Umm, fwiw, I shoot competitively with the M14 and mostly the AR15 with open sights. I shoot a lot higher scores than Expert. High Master actually. Its sure not luck with the scores I fire.
And I can reliably hit deer where I want to out to 300 easy with irons.
LIke you said its what you get used to. You can manage just fine with a 4-6X scope or less. I like a bit more. Anything over about 16x can be useless most of the day.
Heck there are lots of folks that handgun hunt with irons. Last time I looked at a deer with my 4 inch 44, it was about 45 yards. Front sight covers up tons more than what a scope would. Yet they aren't hard to hit.
Bottom line is that even if you can't do it, others can. So it will work.
JB - practice with what you have. Learn to use it and you'll be just fine.
Jeff