Dan I'm assuming by the word "handrail" you are refering to the permenant carry handle model with intergral iron sites. These in "AR-ese" are called A2 models. I picked up a used Bushy A2 in great shape built around the same time. My is a 16" heavy barrel with no brake or flash suppressor but a target crown instead in 5.56 chambering. Paid 600 bucks for that one. One nice thing about Bushies is that chambers and bores are chrome lined. That makes them easy to clean and resistant to rust. Sometimes they sacrifice a little accuracy over a chrome-moly barrel but worth it in durablity. I have had no malfunctions with mine in over 1500 rounds including a lot of Wolf Brand ammo. With handloads it will still shoot 1/2 - 3/4 " at 100 yards. Prices have gone up since election but if price is right they are solid performers. You can mount scopes on carry handle but the bases are subject to loosen as they are designed for quick removal.
I like the A3 flat top variety if you are only going to have one black rifle. That way you can mount a carry handle or scope or red dot sight depending on application. And switching back and forth is easy with minimial point of impact variation if you get good mounts. Another nice thing about AR's is they are modular. For a guy like you with mechanical skills modifying with a new barrel, accessary rails, stock, ect is easy. My second Ar was a Armlite upper on a Del Ton A3 Lower. It has a chrome moly bore with .223 chambering ( a little tighter than 5.56) and "MY WHAT A SHOOTER" with 69gr match bullets. Anyway these things are the ultimate tinkerer's toy. What out they are addictive.