JFettig wrote:clamp it in a vice with soft jaws and take a hack saw or dremel right through the middle of it until you're almost through, should relieve the pressure.
I have heard of people having to cut it out as well. Some people have recommended removing the 10/22 front sight from left to right. I think the key is having the barrel held solidly in a vice, or some other form of support.
On my 1978-dated 10/22, I installed the Tech 200 sights last week and it went very quickly and smoothly. I soaked mine with PB Blaster beforehand, and 2 whacks with a brass punch and it was out.
John