I just mounted a new scope...its a Leupold Mark 5, on a 28 Nosler with a carbon fiber barrel. I can get 8 sheet of paper between the scope and barrel but 9 is tight. What say the forum on distance between scope and barrel?

Largely personal preference. I like mine to be as low as possible without touching. 8 sheets of paper is more than enough space.

Its 20lb paper so thichness is 0.004" per sheet, distance between scope and barrel would be 0.032" roughly.

You can see a little light between the two.

Plenty of room. I have a couple that are about there that I have been shooting for several years with no problem.

Shoot it.

After two separate neck fusion surgeries I have opted to go higher and not closer. For me it is more comfortable and I actually shoot better as a result.

That being said, the above advice is good if you are accustomed to low.

A dollar bill is 0043 inches thick. I just make sure one will slide between the objective and barrel.

Like others have said you are good. i look for about as low as I can get a scope like you are as long as it is at a height for solid cheek weld.