Is it accurate? There'd be no point in having a superb range, with no useful accuracy.
Also, what FPS are you shooting at right now? With .2s?
Assuming you don't care about accuracy then, if you do want some range, jumping from 300 to 500 will give you range.
But it's not as simple as just chucking in a spring.
with higher power springs such as an m150 it causes more stress on the stock internals, such as the Spring guide, trigger Sears, and piston, so you'd need to get a 90 degree trigger set, and a 90 degree piston along with a metal (steel?) spring guide too. Then you'd probably end up upgrading the cylinder too...
as as for the bucking area, you can't just 'buy a bucking' like so. You need to know what type of barrel you have, and then pick a bucking, I use the maple leaf buckings, they get some very good reviews. Along with its counterpart nub. And then you might as well get an AA hop unit.
Also, heavier BBs too, use .36's or .4s, if you try and use .45s with a crap bucking you won't be able to lift them, and your range will decrease.
TL;DR
no, buying a 500 FPS spring will not satisfy yourself in the long run, and you will need to invest in other things in order to get something that shoots well.