Wow those Blasers are nice guns aren't they... I think my father is going to break down and purchase one of the break opens. I didn't even know there bolts were non-rotating, you learn something everyday!

Anyway, I know nothing of the Browning acera, so I guess I am of no help.

If you want a bolt with very little rotation look at the Browning A-bolt, it has the least rotation (60 degrees) of any of the manufactured bolt rifles. I would say the rotation is very confortable and allows you to work it without the annoyance of scope interference. I think the .243 is a very good option, you might want to look at the 7mm-08 as well.

good luck!