The Sight base is pre-shaped to accept the roll pin....but, In some cases some fitting may be required. You can tell by tapping the sight into place an looking through the roll pin hole. It needs to be a perfectly round light hole if not, you can remove the sight and use a fine round file to remove excess material......also, the front sight usually needs some material removed from the flat base of the sight to slide into the front of the dovetail, this can be done by placing some very fine grit sandpaper, say 500 grit on a flat surface and then just light pressing on the sight as you slide it across the paper...it?s a trial and error thing...you want a snug fit not loose.....in a sense your going to have to fit the sight some what, just how it?s suppose to work......they are NOT just a drop in item....hope this helps
This ^ is pretty much right.. every Dawson front sight I've installed, needed fitting, and the semi circluar hole in the base of the front signt needed to be opened up just a bit.. What I did is sand the base of the front sight(using plumbing sandcloth, and, once close, switched to 600 grit) until it fit in the dovetail about halfway in, by hand. Then, I remove the sight, put a couple of small drops of locktite in the dovetail, install the sight, and using a leather mallet I have, pound it the rest of the way in,(usually takes just a couple of light taps to seat it all the way in) and quickly clean off any excess locktite that may have come out. In my experience, a 5/64" drill bit works quite well for opening up the semi circular hole on the base of the sight, I've tried the drill bit in either side of the slide before I did any drilling, and it fit in the left, and right sides of the slide, I carefully drill the base,(from the left side) not putting very much pressure on it at all, as this usually takes must a few seconds,Once that's done, I use a new front sight pin, pop it in place, the pin fits nice and snug, on Dawson F.O. fronts sights the last thing to do before installing the F.O. rod is to snug down the set screw in the top of the sight, once this is done, your ready to install the F.O. rod. With the set screw bearing down on the cross pin, which is a snug fit itself, plus the locktite, this sight isn't coming off anytime soon..