That looks like a proper 11mm rail that the rear sight is mounted on (?). As you state, the cocking arm looks very close if trying to install a red dot or scope. Probably doable with a little thought. There doesn't appear to be a good place on the barrel shroud for a mount (?)
The rail measures 11.6mm across the top, a little wider than the standard 11mm rail. And as you can see from the picture below, it can be done, but not the best fit and the mount must be place far back to make sure the cocking lever can be operated. As for the shroud, it can be removed and you can clamp a mount to the barrel (barrel diameter ø12mm). That is probably the best way to mount an optic sight at the moment. But it seems to be a great interest for this pistol, so I guess someone will make a suitable rail in not too long.
The velocity seems a little low: 476fps @ 8.2g = 5.59j or 4.13 ft lbs. Is the 7.5j an "up to" rating? From your pics it appears to have a velocity adjustment on the back just below the rear sight mount.
150 shots is quite efficient. Is that with a 200 BAR fill? I'm sure it's tied to the velocity but still!
The velocity is where it usually is with ISSF 10m match pistols, between 140ms/460fps and 150ms/490fps. Commercials often claim a little more, but in reality a muzzle energy of 5.5j with 0.53 gram pellets is quite common for those pistols. The Steyr LP50 have just the same performance. The LP50 RF (7.5j) puts out some more, and the LP50 HP (12j) quite a lot more, but at a great expense of the shot count.
The screw at the back is most probably the screw for adjusting the hammer spring. I don't know how much you can gain in velocity by turning it in, but from experience with FWBs earlier 5-shot pistols, Steyrs LP5 and LP50, and a few other similar pistols, it's best to leave it where it comes from the factory. You can probably gain a little more muzzle velocity, but at the same time you will probably also affect the reliability of the semi-auto action. If you want more power you usually need to adjust more parameters at the same time (regulator pressure, hammer spring, choke screw etc.). Those 4.5mm semi-auto pistols are finely tuned mechanics that have sweet spots for functioning and are vulnerable to major changes in settings.
The 7.5j might be an "up to" rating. Drop FWB a line about it, and I'm sure you get an answer.
I haven't done any changes to my P85, except for trigger adjustment, as it performs exactly as I want for my use.
Feinwerkbau has announced a 11j version, and if you want more power I strongly recommend you to wait for that one to be released.
That is a beautiful pistol, especially with the laminate grip! The grip has some silver and black elements to it that really complement the body of the pistol and the air cylinder!
Yours is the only one I've seen in the hands of a consumer. I look forward to more exposure through videos and forum discussions.
Any updates?
The laminated grip looks much better in real life than in pictures.
I need to put a few thousand pellets through it before I can come up with a verdict, but it looks very promising. So far I'm very happy with it.