Interesting you should ask that. I've had the sight for a year and a half. Since this recent post, I looked at the shim that was supplied with the sight. The shim is at too much of an angle to properly align the sight. Why? As I inspected the sight, I discovered that the sight is a Lyman 57SML, not a Lyman 57GPR. The SML is for the Trade rifle. What I did since then is make a brass shim which raised the sight about 1/8". I really don't know the dimensional difference between the 57GPR and the 57SML, but I shimmed it up anyway.
Marv
Marv