KJW M700 Takedown Version, inner barrel

The KJW takes the 650mm inner barrel but i was wondering if anyone had any suggestions. It can take the Prometheus PSG-1 barrel but no one has it. First is the Black Python 650mm Tight Bore Barrel-Regular Hop-up, or Mad Bull 650mm. The only problem with those two, is that they are 6.03mm diameter, and Prometheus is 6.01mm. At long ranges, with .30 gram bbs, will the .02mm difference be horrific or just an inch or two. Also I know these aren't all of the inner barrels I can get so any other suggestions would be outstanding.

6.01 forms a tighter seal than 6.03, and people use 6.03 for like carbines and assault rifles. However if your getting a PSG-1 length barrel go with the prometheus (promy) 6.01 TBB