Thread: How much clearance is needed

Between the scope and a rail .
Will a barrel expand more than say 0.06 of a mil if it gets hot therefore pushing the end of a rail or mount up onto the bottom of the bell of a scope , therefore mucking with the group
I'm not talking whiz-bang calibre here just 30 06.?
I can easily fit a piece of A5 twixt both but seems to touch both the bottom of the scope bell and mount
When looking it sideways it looks , fuzzy, but when you have a proper look there is a definite gap

What do you all think? maybe move it forwards a couple of mill just in case but then want for proper eye relief. Old eyes.