I agree with you....to a point...
Yes,in the case of suppresive fire,M-16 vs Mosin Nagant,Yes,the M-16 user would very easily suppress and destroy the Mosin Nagant combantant ..provided of course,the user of the Mosin Nagant is engaged within the firing range of the M-16..
the M-16 assault rifle has a bit of a shorter range than the Mosin Nagant does,Greater rate of fire yes,but a bit shorter of range. I think the Mosin has about 50 meters up on the M-16 in range.
However,to defend the M-16 a bit,in a normal combat situation,unless the guy with the Mosin has a scope,it's hard to hit (for me anyway) a target,a moving one at that,using iron sights from that far away. However,if the user has a scope,I think that the Mosin has 1 up on the M-16 there.
My theory goes,it doesn't matter how much lead you spray or how big of a gun you have,if you can't hit anything with it,what good is it?