The GHK G5 has proven itself to be one of if not the best gas blowback rifles currently available.
So good in fact that there is very little to complain about - well maybe one thing - the hop adjuster wheel.
Difficult access and material used means that it can be hard to adjust and often damaged as a result.
Our good friends at FG-Airsoft have resolved this by manufacturing a light weight wheel made from stainless steel and is supplied with a replacement O ring. Now you can have a very distinct adjustment potential without risk of damage. Easy to fit as well. See video here.