Quite the difference! Have you managed to get the front sight base off yet, so the nosecap can be installed? There is a trick that I used on a different rifle that had a very tightly banded unit on the barrel. I took a couple of pieces of steel barstock about 2" long, drilled and threaded them for two machine screws to hold them together. The put them in the 4 jaw in the lathe, and drilled and bored a hole through them (1/2 hole in each) the size of the barrel immediately behind the sight unit. Clamped this collar on the barrel behind the sight base and then used a bearing puller to draw the sight base off the barrel. The collar gave something for the puller's jaws to engage. The muzzle must be protected, of course.