Originally Posted by p.phresh
The WE Hi-Capa is their longest running design/variant. You'd think they'd have all the kinks worked out, however the WE Hi-Capa does employ a heavier slide, so gas consumption does increase, but all the internals of a WE Hi-Capa are 100% compatible with TM aftermarket parts, the KJW is less compatible, but is still able to use most parts.
I think if you're planning to run a Hi-Capa on CO2 you should pick a KJW version. They already come upgraded with the red loading nozzle designed for use with CO2. WE Hi-Capas were designed to run on propane and if you choose to run it on CO2 the nozzle will break from the added pressure CO2 delivers.
LOL been there, done that! Didn't learn my lesson though, bought another WE hicapa and had nothing but problems. This time I stuck to propane but some how I ended up cracking the lower frame. I swear I only passed maybe 10-15 mags through the thing. There might be good batches I guess. However, I haven't had any luck with their pistols.