CYM M4 upgrade.

[Jester_UK]

I have this rifle which I picked up for peanuts.

https://www.patrolbase.co.uk/cyma-cm-513-m4-ris-suppressed?pv=2610

I have since bought a G&G Combat Machine and am thinking of upgrading the CYMA to a CQB M4. My idea is to fit a shorter tight bore inner barrel and getting rid of the supressor and fitting a normal flash hider to just poke out of the handguard. 

To do this would I need to replace the hop up and anything else. As this is a cheap rifle to start with I dont want to spend alot of  money . Not looking to increase FPS which is around 280 FPS as is, just increase the accuracy a bit.

Any advice greatly appreciated.

 

[Polluxtroy69]

You shouldnt need to change anything other than the barrel length mate. Especially if you are not bothered about upping your fps. 

If you are looking at paying to replace the barrel then if the one currently in it could be cut down to size. Obviously get it professionally cut and crowned. 

Thats my thought mate but someone could offer even more help.

 

[Prisce]

The hop unit will go on any size barrel. Only reason to change this would be to a better one for a good seal.

The thing you might have to change is the cylinder, there are different types for different length barrels.

 

[Rogerborg]

If you are looking at paying to replace the barrel then if the one currently in it could be cut down to size. Obviously get it professionally cut and crowned.

I did mine with a hacksaw and file, a sacrificial Phillips bit and toothpaste as a grinding agent. The BBs went more or less down-range.

Then when Mrs Borg wasn't looking, I got a ZCI inner barrel from ak2m4.co.uk: https://www.ak2m4.co.uk/internal-parts/inner-barrels

They do them in plenty of lengths, just lop off as much of the outer as you don't want, then measure it up.  No need to fit a flash hider, or even to retain the screw thread if you don't intend to run any sort of suppressor / loudener / tracer unit.

If you're going full CQB on it, consider cutting off the stock and stock tube and fitting a dummy PEQ box for a smallish Lipo battery, e.g: https://www.ebay.co.uk/itm/163179242247  - or for full ghetto style and no cost, you could just bodge something up with tape and cable ties to secure the battery to the body.

No need to change the hop or anything else.  Although with a 233mm ZCI barrel, a rotary plastic ZCI hop ( https://www.ak2m4.co.uk/internal-parts/hop-up-chambers/zci-prowin-style-hopup-chamber-plastic-m4 ), a Maple Leaf rubber ( https://www.ak2m4.co.uk/internal-parts/hop-up-buckings-nubs/maple-leaf-macaron-60-aeg or the 50 degrees from elsewhere), and a basic reflex sight (not shown), it's now my most accurate gun.

 

[Polluxtroy69]

I did mine with a hacksaw and file, a sacrificial Phillips bit and toothpaste as a grinding agent. The BBs went more or less down-range. 

Hahaha

 

[Jester_UK]

I did mine with a hacksaw and file, a sacrificial Phillips bit and toothpaste as a grinding agent. The BBs went more or less down-range.

Then when Mrs Borg wasn't looking, I got a ZCI inner barrel from ak2m4.co.uk: https://www.ak2m4.co.uk/internal-parts/inner-barrels

They do them in plenty of lengths, just lop off as much of the outer as you don't want, then measure it up.  No need to fit a flash hider, or even to retain the screw thread if you don't intend to run any sort of suppressor / loudener / tracer unit.

If you're going full CQB on it, consider cutting off the stock and stock tube and fitting a dummy PEQ box for a smallish Lipo battery, e.g: https://www.ebay.co.uk/itm/163179242247  - or for full ghetto style and no cost, you could just bodge something up with tape and cable ties to secure the battery to the body.

No need to change the hop or anything else.  Although with a 233mm ZCI barrel, a rotary plastic ZCI hop ( https://www.ak2m4.co.uk/internal-parts/hop-up-chambers/zci-prowin-style-hopup-chamber-plastic-m4 ), a Maple Leaf rubber ( https://www.ak2m4.co.uk/internal-parts/hop-up-buckings-nubs/maple-leaf-macaron-60-aeg or the 50 degrees from elsewhere), and a basic reflex sight (not shown), it's now my most accurate gun.

ill probably keep the stock and buy and chop down a tight bore inner barrel. Would prefer to have some sort of flash hider to tidy it up and as the threaded bit for the suppressor is inside the hand guard, that shouldnt be a problem.