My 125th .22 has broken in to a pretty accurate gun if I do my part. I have the spring version and it smoothed out overtime with a few minor modifications. I can get nickel groups at 30 yards with my hand rested on the bag. It does have a bit of barrel droop and the plastic stock could be a little beefier (filled it with foam) but it balances well with the thumbhole. I had trouble getting consistency until a ran about a thousand pellets through it. I decided to tear it down one day and found a bad piston seal which accounted for the inconsistency. Compared to my other guns it feels like a howitzer. If I was to step up to a magnum springer in .25 I would buy another hatsan.
The other issue could be that .25 has a rougher shot cycle than the.22 , at least thats what I've read on this site. When I got the nerve to tear mine apart I noticed the spring was wearing into the plastic base on the spring guide unevenly. I added a couple of steel washers to the bottom of the stem and ground the spring ends flat with a dremel. I also coated the spring with lucas assembly lube which will run, but I didn't have molly tar. I guess this cheap fix detuned the rifle a bit and it made the shot cycle calmer (no more twang) to where it wasn't too hold sensitive anymore. Of course, I did all this because the warranty was up anyway. Mine prefers to be held tight to the shoulder, artillery hold at the balance point midway. It came from pa with a 4x32 optima, never did send it back for the 3-9x32. Used a hawk 4-12x50 but it made the thing too heavy to shoot offhand so I stuck the optima back on it. The first fustrating couple of months after I got it I tried jsb's, cphp, and hnn's but I couldn't get a consistent groups at all. Almost gave up on it too!