Kublai m4a1 barrel i.d

Does anyone have dimensions on the barrel of the kublai m4?

My stock barrel has a I.d. of 7.45mm, I cut the length down so I don’t know what that was sry

Sweet that’s all I really need, do you have the outer dimensions? What kind of barrel are you using now?

Now I’m using a longer barrel, with 7.5 I.d. but I might try even longer again, around 35cm.

Both are those red aluminium barrels, both had outside diameters of 9.5.

I tried a tighter barrel first, 7.3 id but the accuracy went completely to shit and was instantly improved by the larger bore

That’s weird, you must have big balls?


I’ve tried a few types and I’m not completely convinced with the seeming consensus of tight bore barrels being best. I’ve had much better accuracy when the barrel I.d. Is a bit bigger than the gel, theory being it creates an air pocket between the gel and barrel to stabilize it’s flight and prevent crazy random spin. More testing needs doing to be sure though.

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Lol all right…I leave it to the professors on here to explain the dynamics but personally I have small balls Milkies and have good success with a 7.1 barrell.


I don’t like the term “Tight bore”
Should really be small bore because tight makes it sound like you should use a larger dia. gel in a small id barrel. But yes a slight amount of undersize like .1mm seems to work well for accuracy.
I choose 7.3mm because there are a lot of the milky gels available that grow to around 7.2mm compared to milky gels that grow to 7.4mm for the 7.5mm barrels.
Plus I have found the smaller bore also give a good fps boost, that being said there is no right or wrong for this and if 7.5mm id barrels are working for you than thats what you should use :+1:

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I’d be happy to use a small bore, just not sure which milkies are consistently smaller. The ones I’ve used have seemed to vary alot. And as you say, I think a slight gap is beneficial

I’ll keep the 7.5 for now as it seems to be accurate while having enough FPS

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Looks awesome, what have you done to the internals

There doesn’t seem to be anything consistent available lately in Milkies !
But probably over 90% of the ones available are of the smaller size range up to 7.3mm and only a few can grow above that.
Demineralized water does make gels grow slightly larger as does hot water but I refuse to spend another $3 or $4 on water !


Stock kublai gearbox
Stock tappet and return spring
Stock cylinder
Stock head and nozzle (nozzle rubber head moved back 2mm)
Green o-ring
Metal 18:1 gears
Nylon plunger with metal 7 hole head and metal ladder with one tooth removed from the front.
1.4 uneven spring
Fighting bro’s sector delay chip
Chihai purple motor
11.1v battery
Battery connector changed to mini tamiya

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