RE: BSA scopes
It depends on the model and price point you pick. A cheap scope is a cheap scope, I don't care who's name is on it. If you are getting a 24 power scope for 100 bucks you are probably not going to be very impresssed. A good scope of that power is going to cost around $300 or more. They had to cut corners somewhere to get that price. And the two biggest are Optics quality and Quality Control.
I have probably owned 5 BSA's I think. All of them functioned just fine on guns from .22's to a .50 cal inline and a 12 ga shooting slugs and turkey loads. The optics on some of the cheaper ones was not too great. I had a contender that was 4-16x50 and it worked ok, but at 16 power at 100 yards it wasn't very clear. And it fogged up during crappy weather. However the Catseye and Panther scopes are pretty nice, comparable to a simmons 44 mag or aetec, but they cost more too.
If you are looking for a 20+ power scope for a centerfire I would look at scopes in the 200 or above price range. I have an Alaskan Guide scope from cabela's and really like it alot, but it was almost $400 (6.5-20x44 mildot).
My advice would be if you have a limited budget get the best scope you can get for that kind of money. You may have to alter your selections though. A lower power hunting scope without all the cool features for the same money will be a much better scope. Let's say you are looking at two different scopes. One is a 6-24x50 scope with an adjustable objective for around 150 bucks. The other is a 3-9 or 10x40 hunting scope without the adjustable objective for say $200. The $200 hunting scope is going to blow the other one out of the water in quality. And even though it will have less overall magnification it will look much better because of the better optics and actually be more usable.
Next time you get the chance look at some cheaper high powered scopes and then compare them to a better quality scope. In some cases the difference will be like looking thru old plexi glass and a brand new glass window. And at longer ranges this is even magnified.
That's my opinion any way.
Paul