I was trying like hell yesterday to remove the rear sight from a 1953 M64.
I whacked that sucker 20 times with my Wyoming Drifter. No bueno. Did not budge. And I am not a newbie using the drifter.
Pulled out the punch and hammer and had the rear sight out in 10 seconds.
I like the drifter, but you ought to have multiple methods so you have a back-up.
Heat & Kroil
Big hammer