Frankly if you're not doing something really stupid with your gun -like running a hot spring or high ROF setup without proper supporting components- even proprietary stock guns should last a good, long time.
In the 6 years I've been playing, the only internal part of an airsoft gun I've actually broken was the stock KWA cylinder head on the KWA G36, which was not an uncommon failure.
Hell, my 6 year old CA G36 is still running it's stock tappet plate. Some things WILL break eventually, but being a highcap n00b with today's really hot guns is a great way to prematurely break stuff.
"Someone in a Prius tried to race me at a stop sign the other day. I couldn't believe it. I had him for the first 100 feet or so but I can only walk so fast."