^^You know what I'm developing as a policy toward CYMA internals, GK? Leave 'em alone. They're meant to be loose and noisy and coated in earwax - they work best that way. You put a TBB in there, you'll need a spring downgrade. The next thing, you'll be wiping all that earwax out and doing a nice shim job. Then you're going to check the compression and find it's shit. So you'll want a new O-ring, maybe a piston head. A new piston head on that nasty looking off-white plastic piston...? So that's a nice new SHS blue one. And that crappy no-O-ring air nozzle...? No way, man! What you want in there is a nice shiny ali one... going into the stock, who-knows-what-degree hop rubber...? Nah... gotta be a G&G Green at least, maybe a Prommy Purple for a marksman rifle... maybe get a new CNC hop unit to go with...
And by then, if it's working as well as it did when it was stock, the noodly-appendaged god of airsoft is smiling on you...
Edit: OOps, i almost forgot! Thanks for the info on the sling point. Have you got a linky?