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Cm16 Upgrade barrel *HELP NEEDED*

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Hello, i have had my cm16 with me for a good year now and i feel that upgrading my inner barrel will be a good idea. So i was wondering if i could use the Madbull 509mm (6.03mm diameter) tightbore and i was wondering if you thing it would work well with my CM16 and also if i should invest in a new hop Rubber and Bucking, any recommendations are welcome :)



Thank you


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a high quality barrel and air seal will improve your fps, a decent hop nub should improve the hop. Both will give you to an extent better range and accuracy. If replacing the barrel then I'd say do the hop bucking and possibly nub at the same time. Not just because you'll notice a larger improvement but also to reduce the amount of times you pull it to pieces as stripping guns down regularly will increase the chance of putting it together wrong (although familiarity with internals is a good thing).

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509mm is abit too long, and i dont know if the standard cylinder is ported for a barrel of that length. iirc standard length of a CM16 is 360'ish mm


in any case what aspect of your gun do you want to upgrade exactly ... a TB barrel will only give you a mild FPS increase.


if you want range, use heavier bb's. if you want accuracy use branded bb's.


as for the hop, if your hop rubber is worn out, a standard G&G rubber is pretty good, or a TM rubber

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If it's the carbine length 14.5" barrel then you want the 363mm inner barrel.

509mm is ~20" (that's M16 / AK length) so unless you have a long arse suppressor you want to stick on there, I would suggest the former.


The QUALITY is the most important thing when it comes to inner barrels. Length is not really as important. 6.01s are generally avoided too because they'll require more cleaning (compared to a 6.03+)

Speaking of which keeping your gun maintained will improve performance and consider using quality BBs will help too (Blasters are fine, BB Bastards -there's another brand also I can't remember- are supposed to be excellent, and 0.25 or above rather than 0.20s)


You could get better than Madbull but it would be PDI / Prometheus which are much more expensive. Madbull are cheaper and widely available so I'd say it's a good upgrade choice.

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Longer barrel doesn't always mean better accuracy. The barrel only needs to be long enough for the BB to stabilise centrally within the barrel, cushioned by the air forcing itself around the bb. The quality of the hopup is key to accuracy. A tight bore barrel may improve things slightly but mainly it will just increase fps a bit.

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CM16's come in wide range of barrel lengths aprox 220 to 363 depending on actual model

110/120 on FireHawk and 220 on short raider to say 363ish on m4a1 carbine


your long raider has a 357/363 barrel so most likely has some ports say 3/4 to about 80% of the way back I would guess


your cylinder is almost deffo ported to provide the appropriate amount of air

509 is way way too much and almost deffo result in absolute pi$$ poor performance if you fit it

(509 is for full unported cylinders and at/over the limit unless you have the longer cylinders like sr25/l85/svd etc.. - which you dont have)


how much/often have you used it - if skirmished at a site what fps is showing ???

more importantly clean barrel first - even just with a dry bit of kitchen tissue

check how it performs and how you feel it did perform in the past.....

(also in colder weather range can be effected anyway)


most likely it could do with a few tweaks after a year in BUT only by somebody who knows what they are doing

(take it from somebody who first few box's didn't work too well and lost $hitloads of bits in process)


dunno what range and power you are expecting most G&G's are about 330 out of box

and this may drop to 300 in say 6 months regular use - all guns/springs lose some tension

but it may still perform ok.


it would be good to know the fps - spring/seals may need changing

but this requires opening up box - by somebody who knows/careful

(if seals all worn and poor fps then all the super tbb barrel + hop won't be as effective)

clean barrel - see if that helps it is free

change bucking - another cheap thing about a fiver


get it chrono'd properly if possible or you are guessing with coke can tests

or unless you are very very very good/god walks on water can kind of roughly tell how good it is

(hence why they make chrono's)


decide exactly just how pi$$ poor ya gun is first - they all lose their ooooomph a bit

clean barrel & new rubber is first thing like many have said

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My M4 raider stripped the piston so new piston, cylinder head and o ring nozzle were put in but spring was changed down to an M90 (same as my G36C, over site limits) my sons M4 dropped down to 260 FPS so i looked in the gearbox, bit of silicone oil on the piston o ring and its back upto 330 FPS

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