The specific model number is often stamped on the underside of the forearm wood, at least the 409/410 series guns have it there.
I think JB may be correct, but the GR3 had an Italian model name too & I don't recall what it was just now.
I like the articulated front trigger.
The Roman numerals and letters denote the year of mfg. as I recall. Someone here will likely post the link for that information for you.
Not a lot of help, but hope it helps a bit anyway, I don't have any ref material handy where I am.
