That gun is the only one I've owned that shot .177 RWS SuperDomes well and out to 30 yards it worked well using head shots (between eye and ear). I owned that gun several decades ago and it was fitted with a Beeman 1x-4x scope which was adequate for sniping at my 25 yard zero distance.
I used that gun for 20 years and the spring never did break but it got very week. There was a squirrel on my bird feeder when living in West Virginia and I shot the squirrel in the neck at about 20 yards. With the shot the squirrel scampered up the tree the feeder was hanging on so I actually thought I missed the nutter. A couple weeks later there was "another" squirrel on the same feeder, however I dropped that one with a .177 Super dome that went between the eye and ear. When I retrieved the nutter (I eat those things) I felt a lump on the side of the neck. LOL.....there was the skirt of a .177 SuperDome sticking out of the hide with the pellet head inside. Kinda reminded me of a Frankensquirrel!
That was when I realized that I didn't miss the squirrel that I shot a couple weeks earlier, the HW35 simply no longer had the moxy to put a pellet through the looser fur at the side of the neck, however with the tighter hide being backed up with the skull there was sufficient penetration.
Anywhoo......soon after that I ordered my third adult springer from Beeman, a .177 R10 and I thought the R10 was as good as the HW35 was bad for squirrel sniping. The R10 was lighter, had similar cocking effort, yet shot a SuperDome 100fps faster. The HW35 was sold years later after replacing the spring with a Maccari spring kit and the buyer was happy to get it after taking a few shots.