I havent put it on my 450b, but THE best scope I have ever owned is a TASCO World Class 3-9x40. I recieved it 20 years ago and it needs little to no adjustment year after year. Which when you consider it bounces around on my 4 wheeler for 5 month each, I think that makes it a pretty damn good scope. I purchased one (59.99 wally world) a few years ago and have recieved the same perfomance for it as well. It may not be the best in low light or meet Leupold standards, but for the cost it can not be beat.
With that said I may be the lucky one who got two well made scopes, but I think that is with everything mass produced in this world. And I can not justify the cost of some of these scopes I have seen and heard fail just as bad and the cheap ones.
But at $139 that is a good deal!