I removed the rear sight (left to right) with a punch and hammer, without losing the springs. The LPA replacement arrived yesterday and was returned today.
FYI:
Although LPA advertises it for the third generation, .45 calibre Smiths, there is no way it will fit, either right to left or any other way. It is not cut deep enough to clear the raised part of the slide.
I have found a Pachmayr adjustable sight PAS SW 45-2, which is said to fit an SW 645 or 745. Can anyone say definitely whether the 4506 is cut the same as the 745? I'll appreciate your advice.
For those who question the shooter's ability, I have been shooting 38/357 and 9mm for several years, 45 Auto for only six months. Nevertheless, with a Taurus PT1911 in .45 Auto, I manage to keep shots in the black and do not find the recoil worse than the 9mm.