Yes they are soldered on. First you have to remove the front sight post from the barrel, also soldered on and held in place by a set screw. Set Screw is under the sight blade.
The barrel should have a small hole at the back end of where the sight rests against the barrel step. The screw that goes into the sight (buggered hole in pic) has a dog point and locates in that hole (sorry no barrel pic).
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-Peter
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