6.01 vs 6.03 barrels!

Some of you may remember a large thread a while back on AEG accuracy and some research efforts put into finding out what produces the best accuracy at long range. The thread last I recall ended without all possibilities being fully test. Finally I have had a chance to do that, I have a stock 6.05mm, Prometheus 6.03mm and EDGI 6.01mm bore barrels for an otherwise stock KM16BR late 08 model. It is equipped with the G2 bucking and a Firefly Buffer Rubber for AEG (Normal) http://www.airsoftat...uct_p/63314.htm . I have used the same G&G .25g BB's throughout all of my testing. Now here is what I have noticed shooting at a 200ft range (measured).

KWA 6.05mm Brass: worst performer overall at 100 ft and 200 ft ranges. However this may be partly due to the poorer tolerances as this is an OEM barrel and not a precision manufactured barrel such as EDGI, Prometheus or PDI. Groupings ranged about 16-24 inches at 200 ft when no wind. Keep in mind the new KWA 6.05's have a better build to them, so they may perform better.

Prometheus 6.03mm Stainless: best performer at 200 ft range, second best at 100 ft. Groupings were 6-12 inches at 200 ft , which is well within the limits of hitting a human sized target.

EDGI 6.01mm Brass: second best performer at 200 ft range, best performer at 100ft. Groupings were 10-16 inches at 200 ft, which is still able to hit a man sized target, but may require more than 1 shot on average. This barrel also becomes dirty very quickly and quickly degrades in performance.

This confirms my theory of a certain clearance for best accuracy at maximum range. For a DMR, using 6.03mm or 6.04mm bore barrel with 5.95mm bb's gives us a clearance of 0.08mm and 0.09mm +/- 0.01mm. going to a lower clearance than that will increase accuracy inside of a 100 feet where the backspin has little affect on the bb still, but decreases accuracy outside of a 100 feet where the backspin starts to become an important factor in trajectory. I think we can conclude from this that there needs to be a minimum clearance between the barrel and bb in order to avoid altering the backspin the hop-up puts on the BB. clearances under 0.07(0.08mm-0.01mm as a minimum in my particular test using the 6.03mm barrel) start to alter the backspin the hop-up puts on the bb, so the axis of spin becomes more random as the bb rubs the barrel. Clearances that are to high will also have a similar effect as turbulence is produced from significant pressure loss(uneven pressure would result in more bounce inside the barrel), causing the bb to bounce in the barrel and alter the backspin. I would say as a guesstimate that going over 0.10mm(0.09mm+0.01mm as a maximum using a 6.04mm barrel) clearance will start to result in to much pressure loss. Please note the groupings are estimated based on a target that is approximately 14 inches in diameter, a tree in this case, they are not absolute. Barrel uniformity is also important, the smoother the bore the less likely it will be to alter the backspin if the bb comes in contact with the barrel wall.

It seems there is a craze for 6.01mm barrels because everybody knows that if its a tighter tolerance then it must be better, right.....??? Forgive my sarcasm, but I find misinformation frustrating and the lack of desire to take some effort to study and analyze the problem even more frustrating. Yet the misinformation or opinion gets spread as if it were fact in the airsoft community, at least here in Ohio :-(. In any case this is what I have found during my testing.