KWA G18C Upgrade

[Nakor]

Hello,

I *think* this is the right place for me to post this. I recently bought a KWA Glock 18C and it came with the plastic slide and barrel. I want to upgrade to a metal slide and barrel, and I am not certain on what else I need. Far as I can tell I need a new spring guide and spring...but not sure what else.

The best stuff I could find so far is here:

http://www.007airsoft.com/products/htm/metalparts.htm
(most of the way down under Metal Parts for Short Arms "Glock 18C Metal Slide and Barrel" SKU#70058)

http://www.007airsoft.com/products/htm/upgrades.htm
(bit more than half way down under Parts for Short Arms...not sure if I need the tune up kit, or the tune up kit and the metal recoil rod...etc.)

If you know of a kit that has everything I need, or simply what items and where I can get them, please point me in the right direction. From the looks of it it will cost a chunk of cash lol, but I already knew airsoft was expensive.

Also, I'm using Green Gas as that's what came with it, but I don't think I'm supposed to. My gun seems to sometimes break the BB's on the way out and sometimes an extra BB slides out upon or after firing. Any idea why? The BB's that I got with the gun seem to be high quality. They are KSC "Perfect Brand" .20g BB's.

Thanks.

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Side note: I had never fired a GBB before. I had no idea how cool they feel. I am however hoping that a metal upgrade will slow down the ROF for full auto.