Here's the thing when calculating the volume of the barrel that 0.02mm (if it's 50/50 split would equal a 6.01 average) means nothing the difference between a full 5.98 and 6.01 at that length is 200cc roughly which wouldn't make a difference to the ratios.I may have missed this so forgive me if my weekend eyes failed me!
Currently using an AA cylinder, Springer Custom Works piston and guide, and an Edgi 430mm barrel. Now, for a 6.03mm barrel, the guideline weight is .43g but mine is actually a dual bore barrel that runs from 6.03mm to 5.98mm....and I use .48g BBs. Now, I have no issues generating hop, and accuracy/consistency is quite acceptable but I'm always looking for more......and I would guess mine is more than slightly over-volume......
So how much difference will a switch to a different weight actually make, and in the words of Paul Harrel "Is it enough difference to make a difference"?
Now a theory I've mentioned is that the 5.98 is much more aire efficient and changes the ideal cylinder/barrel ratio but no one had tested fully yet.
With that said to reach optimum efficiency would be using lighter bb's than .48 I believe, but if your range and grouping are good than no point in changing.