But I've got to disagree with you here. First, the preload on the spring in the 350 isn't 100 pounds, maybe half that. And second, RWS guns are notorious for being shipped practically devoid of lubrication. Yes, doing some research first is necessary, and caution is always required when working with springs under compression. But a simple lube job isn't rocket science, and scaring the hell out of people isn't helpful.
I strongly suggest a good spring compressor, either purchased or home built. There are plans all over the place. If you build one, allow for plenty of stroke, the preload is pretty long. I also recommend buying a lube kit from Macarri before opening the gun up, basic info on what goes where is on his site. But this is one gun that I don't agree with the "shoot it for awhile first, then tune" advice. There was a huge difference in the way it shot after I lubed mine. And all I did was lube it, the internals looked pretty good. But it was practically bone dry, just lubing it greatly reduced the spring twang, vibration and torque. It was still a bear to shoot, and it definitely cured me of springer magnumitis. I've since moved on to PCP's, and the 350 had a lot to do with that move. But a good lube job was very worthwhile, I just wish I'd done it right out of the box. If you can afford a pro tune, great, but just doing a good lube on these guns makes a huge difference. And it's a difference that I don't believe can be matched by "just shooting it". Just my opinion, hope it helps. Later.
Dave