Every gun shoots every ammo differently. You can't make more than very vague generalizations about XXXX ammo being more accurate than another. Many(Maybe even most) guns will be more accurate with some cheaper brands than some more expensive brands. So it's usually worth it to spend a day finding the cheapest ammo that gun shoots well enough for you.I admit to a great deal of stupidity on this issue. I've spent my life shooting at different points, sometimes quite often, but generally I've been pretty poor. So, I never really appreciated differences in ammo.
Which of course begs many questions.
I started getting into bench shooting because I put a scope on my winny 9422 after owning it for 32 years. I was shooting the cheapest ammo I could find, but found I could put them all within reasonable groups on a palm size(gopher head sized) target.
So, I decided to get a better rifle. A 453 Varmint in 17 HMR. I was immediately able to group better and enjoyed the experience a great deal.
However, I bought more expensive ammo of different brands, weights and speeds for the winny and found between brands I had to spend a great deal of time sighting in...it just seemed one brand never performed particularly similar to the next, even if it was only a grain of weight and perhaps 100-200 fps.
With my 453 I recently shifted from off the shelf CCI TNT to an off the shelf winchester load...however even though indicated fps was the same, I found my groups became much different when I shifted from the winchester, which was actually cheaper, back to the CCI which was slightly more expensive.
I'm sure I can be directed to a sticky somewhere, but it seems to me from experience that the expense of the ammo is less important than consistently using the same ammo. Basically, whatever you get used to will perform better, because you've sighted it in...I realize this is a tenuous proposition at best. I do have some slight proof that middle of the road (in cost) ammo performs better in my winny than the cheap stuff or the top of the line stuff.
With my 453, I'm strongly tempted to shift back to the cheaper winchester ammo.