Wow, must be an oldie to have a dovetailed front sight. You would be best suited soaking the bugger in penetrating oil, give it a shot twice a day for 2-3 days. On the 3rd day heat the dovetailed portion of the barrel, not the sight, with a torch till it's really hot, 2-3 mins. Strike the sight( be careful not to hit the barrel when it's hot or you could bend it), on the right hand side of the sight looking at it from the rear. You will want to have the barrel firmly supported in a padded vise.
If you have to recur the dovetail though, I used a medium single cut bastard file on edge for the bulk removal, then a triangle file with one side ground flat to get underneath the dovetails, and I finished the touch up using a set of needle files, but you don't really need the needle files. Let us know how it goes!
It certainly is an oldie. My wife's grandfather bought it used in the 1960's, the exact age is unknown. It's actually marked as a 'Sure Shot Repeater .22 CAL.', which is a Model 60 rebranded for Sears.
It's actually in pretty rough shape. Were it not for sentimental value, it would not be worth near the time, effort and money I am putting into it... but such is life!
When I got it, the action was rusted shut, and the barrel could not be seen under the pitting. Also, the stock was broken, the inner magazine tube is long gone, and the end of the barrel is heavily pitted and corrodes.
At this point, the action is smooth as silk, I have most of the pitting out, replacement sights and a refinished stock. The remaining tasks are to finish the metal work (including a cut and recrown), cold rust blue it, and I need to unpin the trigger shoe, and grind it out so it catches the bolt correctly. Oh, and locate a proper magazine tube.
Yep, totally not worth the time an effort....
Edit: If anyone has any tips for regrinding the trigger shoe, or even a spare on kicking around they want to sell, please - let me know!