The stock mws/marui barrels are beat rounds on the most "magic" inner barrels so generally doesnt make sense, unless you wanna play with the fps, though I changed for a Maple leaf 300mm one for this reason and because I running Maple leaf bucking (the bucking and your inner barrels mouth must to be matching and air-tight 100%) , its just depends on your upgrade parts.
In order to find the best result in accuracy these things must to be matching :
- Consistent fps (on semi auto)
- 100% air-tight
- barrel mouth+bucking+nub are match 100%(length,shape,tightness)
+ the nub contact on the right place with the bucking and the hop arm push it down from and in the right angle (check the laylax hop unit)
So the end of the day the barrel length and diameter doesnt takes much without these things but not at all in my opinion.