Four inches at 50 yards wouldn't be too bad a group if you were shooting off hand standing, but if you shot off a rest, the gun even with bad eyes should do better than that.
Old eyes can do that to you though, and I know all about that!
I have a 45 LC carbine that I felt the same way about in that I didn't want to spoil such a compact little rifle by putting a scope on it, but I wanted to hunt with it, and low light and my eyesight wouldn't allow that to happen without some glass, so I ended up putting a scope on it, and never looked back!