it really depends on where it is flaking on whether or not it will effect performance...you cant just say it wont effect performance....
if its flaking along the shaft the seal between the internal blast guide oring and the ram shaft could be compromised or the drag and eventually accelerated wear could occur between the ram shaft and inside of the blast guide....both of which are very bad and will eventually lead to problems in efficiency and velocity....the original blast guides are defective anyways....if you clean it, hold it up to the light and see how rough the inside of it is.....you'll quickly realize what I mean.
but if it were my gun I would replace it no matter where it was flaking. you dont want pieces of nickel, or anything else for that matter, floating around inside of your engine.....call blast they can hook you up. they went away from the original nickel plated ram shaft for this very issue and now are not plated and can easily be seen by there dull finish.