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You have a staked on front sight. Its not terribly difficult to replace yourself, but it's not nearly as easy as a dovetail.

Brownells has a front sight staking tool you can use, and you would of course need the proper sized sight. Depending on when yours was made, you'll either need a "wide" or "narrow" tenon sight (depends on when it was made). You place the slide upside down in a fixture to hold it (vice, make something out of a couple of 2x4s, whatever), then place the sight in the channel (optionally with some red locktite), then place the staking tool on the sight, and proceed to whack it with a hammer and spread the tenon out.