Williams no longer lists the FP-Henry in their catalog, but the Marlin FP-336 sight fits perfectly, and it does not obstruct the hammer. If you go with the target knobs including the gib knob screw for locking the elevation, you will have to shorten it (the gib knob screw) from .816" to .666". I just ground off the required amount from the screw threads and chamfered the start of the threads, it works perfectly! I don't know why Williams doesn't sell a shorter gib knob screw, since with many of the FP sights the gib knob screw has to be shortened.
The Williams FP-336 will work with the stock blade site, but I wanted to install a Williams fiber-optic blade sight. It was a simple change, a few taps from a small hammer and nylon drift and the blade sight came out. I had to use a fine 60° triangular file to get the new blade sight's dovetail to fit, just a few strokes and I was able to tap it in with the nylon drift.
I also got an 1.25" M1907 leather and brass military rifle sling from someone on ebay — it looks good on the Henry.
andrew678122
