It can be done fairly easily if you do it properly.
New sight will almost always will require some fitting. Don't force them in unless they are filed and can be pushed in about 1/6 way in with hand.
I find that thin plastic handled metal nail file (called diamond file I think
) works best. They work well in tight spot between sight blade and dovetail. Buy one with sandpaper texture instead of checkered pattern. It's only about $.99 at wallgreens. Thick metal file will not work.
Slowly file away corner edges, then evenly on the front and back slanted flat surface.
Once filed enough, you should be able to push it 1/4 way in with hand and halfway in with minor tapping. sight goes in from left to right with muzzle pointed away from you. Tap on the base of the sight instead of blade for better leverage.
Finally secure it in the vice (must!), then tap it in with white nylon sight punch ($ 3.00 from brownells). If they don't seem to go in, don't force it in, punch it back out and file slightly more. Anything other than hard nylon, such as brass, seems to ding the sight. Never use a metal hammer incase you miss the punch!
You should buy $4.00 nylon punch, $.99 nail files; and everything else, from nylon headed hammer to vice, can be either borrowed or found in many gun range back room.
This is fairly easy for me, and I do flawless jobs. If you have further questions please feel free to E-mail me.
As for Local Gunsmiths, I don't use them anymore because they:
1. keep the gun for whole week for 10 minute job.
2. Over charge for the parts.
3. Scratch the gun, and don't take the blame.
4. Do a poor job.
5. And when they screw up (which some often do) they do half
ed fix, instead of
replacement.
Also, the knowledge gained from doing it yourself is priceless.