Some sights are very tight, some aren't.
If you must move it, be careful.
Pad all around the sight to accidently keep from dinging the receiver.
Layers of duct tape is usually enough to prevent a scratch.
Pad the receiver in a vice and use a brass rod and hammer to knock the sight base over.
Don't hit it hard enough to bend the sight base.
If it moves OK.
If it is really tight quit while you are ahead.
I've never damaged the receiver but I have bent a sight taking it off.
One easy way to see if the barrel is screwed in to make the front sight "square" with the receiver is to,
Strip the receiver, slide, trigger housing, etc.
Pad the receiver and hold it lightly up side down in a vice.
Use two straight sticks, like 1/4 inch square and about 14 inches long.
Lay one stick across the flat front of the bottom of the receiver.
Lay the other stick across the bottom flat of the barrel.
The sticks should be parallel.
Which, of course will make the front sight 90% to the receiver.
