Welding standards allow GMAW using short circuiting transfer (I believe that is what you are asking about) with certain restrictions. The restrictions limit the thickness range of the production WPS based on the thickness of the test coupon used to qualify the precedure, i.e., PQR.
I am not familiar with any welding standard that permits the use of GMAW-S without qualification by testing, i.e., there is no "prequalification" as there is by AWS D1.1 for several listed welding processes.
Another consideration when qualifying the welding procedure is the type of base metal used for the hydraulic cylinder. High strength low alloy steels are commonly used and require preheat and in some cases post weld heat treatment. These variables must be taken into account when qualifying the procedure.
Once again, you did not state what welding code or standard you are working to. Without that information we can not provide you with better direction. However, most welding standards or codes allow you to do what you want if you "prove" the process will produce the required results and you control the process in production.
Best regards - Al