Hi Les

Yes the front sight becomes harder to acquire!

The rifle was made, 500/450 3 1/4" Magnum, in 1906 and the second set of barrels, 357 Flanged H&H Magnum, was made sometime in the 1950's by H&H. I got this by confirmation from the maker and the timing from the barrel number (separate to the serial number) corresponding to the early-mid 1950's from tables in "The Shooting Field'.

The front sight setback seems common on 375 barrels by H&H, not sure why! Certainly have seen it on other doubles in 375.

Cheers, Chris