Yep I had a TM recoil after having a ghk gbbr. Loved my ghk but the mags at the time I had for the ghk were a pita and the cold weather performance was too inconsistent. Thought the ngrs was the next best answer but I found it sterile compared to gbbr, the ngrs got shelved. I stuck to my TM gbb pistols for the past 10 odd years and never missed a beat for me no hpa needed, not sure what's up with your px4 but not sure hpa is the answer. I've since got me an mws, only been out one game so far but I do like it.