Also here is what the guts look like for anyone interested
http://www.popularairsoft.com/review...support-weapon
Looks like a standard nonported cylender to me but hard to say without a recerence pic.
Also some more helpfull info here looks like at 650mm the cylender to barrel ratio is 1.2:1 not really ideal on all systems but if the l86 has good airseal like mp5's and AK's do i dont see it as an issue being slightly under volume.
I run 455-509mm in all my 3/4 and 4/5 cylender guns and have no issues. (all m4's by the way and they have a fair ammount of loss between the hop up and nozzle due to the design of them.