I’ve seen the adds and tried a little research. Apparently the company is Polish? I can’t find any reviews of the product. The numbers they are claiming are pretty much the Hatsan factory specs though. The counter wound spring is an interesting concept but I’m not sure it works the way they claim. The lack of a full sized spring guide seems a mistake to me.
Some 10 to 15 years ago, there was a true Gasram Craze, with Hatsans being one of the most-mentioned makes where a gasram is supposedly a vastly superior choice to a coilspring. Of course, manufacturers had a HUGE incentive to boost gasram sales, so they could sell the same gun twice. On paper, the gasram advantages for clear and plenty. Every one of these (velocity, recoil, noise, spring strength loss etc.) can be easily countered by real-world coilspring examples, and the biggest downside of all to gasrams - the nasty consistent cocking resistance - was never brought up, but I digress.Fast forward to recent times, and a huge number of gasram aficionados have had their gasrams leak, out of the blue, often after an extended period of no use of the gun. Does sound an awful lot like living with PCPs. There are ways around those failures, as Steve points out. Not every springer guy has a high-pressure hand pump available, though. Having to have them is exactly what many springer guys want to avoid in the first place.