My Brother in Florida just built one like it this past week, using some $400 (original price)
"Bob Revolution" model Jogger baby buggy he picked up at a garage sale for $10, has front and rear brakes, bunch of other stuff he had to take off to lighten it and get it to fit in the trunk of his Kia.
He built the gun holders, should have thought about those gun Grips like you used , have seen them at Wal Mart. Would have saved him a lot of work.
Nice job on yours!
It balances really nice with 1 gun, haven't tried it with two yet. They weight of the ammo and other junk in the bag ( chokes, choke tools, Beretta multitool ) helps as well. Have a cooler bag that goes under the range bag in the seat
I saw this old thread. I just built one for myself, out of a old jogging stroller and some Kolpin Rhino Grips. The milk crate is just attached by bungee cords. Thats where I keep the small cooler with drinks/food.