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!