MP5 Upgrade Hop-Up
 

Afternoon everybody, I recently picked up a CYMA MP5A4 as a new project gun and I was wondering if there are ANY aftermarket improved hop-ups. The cyma hop-up appears to function just fine but who knows how long that will last.

You mean the hop-up rubber or the chamber?
For the rubber, replacing the hop-up rubber in a CYMA gun with a better one can give you a great increase in accuracy, in most case.
For the chamber, the general rule is don't replacing a working-fine hop-up chamber unless there is a very good reason. A small variation in dimension (mostly, the length) can give you a very weird result and it is kind of a pain to correct it if you are not familar with this type of issue.

My cyma mp5k with a stock rubber shoot 100-120feet And now with a bucking pdi w hold I shoot 150-170feet with a better groupping. Just change the rubber

I've already swapped out the rubber I was just curious if there were any upgrade hop-up units its my can't leave anything internal stock OCD kicking in :P

Are you getting perfect compression from the mechbox?
What brand and weight of ammo are you using?
What kind of barrel is in there?
What muzzle energy are you shooting at right now?

1) 100% no (its all stock cyma my parts are en route)
2) Eliteforce .2s/.25s
3) Stock cyma
4) 300~

but yeah the point of this thread was just to see if any EXISTED to sate my curiosity.

Sorry to hijack the thread

How can I improve seal and compression on the mp5k?

I just installed a 247mm TB and new bucking for more accuracy.

clean and regrease the cylinder, change any parts that have air leaks

did you check the airseal first?
fire in semi with yer finger pluggin the nozzle.
take the barrel and hop up assembly and plug all the holes but one with yer finger and suck or blow on the other hole to see if there are leaks.
mp5's are prety good on seal like ak's

I'm interested in this as well. Gutting the compression system on these guns makes them pretty great, but the chamber itself is definitely a weak point. It works well enough left as-is, but since it's just crummy poly built to low-tolerance it has a hard time holding hop when set to anything higher than 'meh'.
It's pull-arm type but I'm not sure which (arm is hidden by the ejection port, NOT old TM/ CA front-pull), and eyeballing it indicates that wheel-type V2 chambers won't clear.

It's not a 100% necessary upgrade, but it's pretty much the last link to making these decent guns pretty great, and the stock chambers will fail eventually.

Edit:
This is also important due to nozzle matching, and the stock nozzle is crap.