Wow what a great thread.

Nice on the cooling gizmo. I think I see a side job in your future!

Somebody tell me about the rear sight. Was that cut by the previous owner? Maybe to accommodate aging eyes?

Reason I say it is for years on my iron sight "bad weather" and bear guns, I have widened the rear notch substantially and then used thick front posts. I have 20/20 distance vision far away but up close it's all fuzz. The wide rear sight gives both precision and fast acquisition. Looks like whoever owned your double felt the same way?