I've heard tell that a 25m zeroed PCC can hit a gong at 300m, but the hold is top of the 6m backstop berm.
I've not yet managed to get to where I can test longer range with my TNW Aero. Not the same PCC as the one under discussion, but similar specs to the Ruger. Mine has an 18.75" 9mm barrel and puts out Remington UMC 147gr at an average of 138fps, for 350fpe at the muzzle. Using Chairgun Pro software with my setup, it's showing this bullet still having 195fpe at 300 metres, and a holdover with my zero at 55 metres (that's the second zero, using a 1" KZ - first zero is just under 24 metres) of about 4.34 metres. That's a relatively slow projectile, something I've decided to use as I prefer keeping the noise level a bit more moderate. At 150 metres holdover is 71cm, the same as my shoulder to fingertip, so not too hard to visualize when aiming. Here's Chairgun's trajectory using the yards equivalent of 300 metres as the longest distance:
I've got a Burris rimfire 2-7x scope mounted on a Burris P.E.P.R. mount, and according to Strelok on my phone these parameters put the bottom of the thin reticle just about exactly on my bullseye at 150 using 7x zoom. Again, not hard. 300 will be more challenging, but to be honest I'll only rarely shoot it that far as for 9mm it seems a bit silly. Mostly I'll be shooting out to 100 yards - been using an MTC Viper Pro 5-30x scope on my main air rifle for a few months and its range tape on the vertical turret is calibrated for yards, so my rangefinder is as well and I'm getting used to using Imperial distances for shooting. At 100 yards, the Aero should be right on target with holding on the second hash mark on this reticle at 7x.
I'll do the same with subsonic .22lr, occasionally testing myself at greater range but only for fun, not something very practical for hunting. Certainly won't be shooting any propane tanks with either! I'm not a big fan of loud noises. Hesitated a long time on getting into firearms from PCP airguns for that reason more than anything else. But I've got good custom fitted earpro so what the heck, explody shooting is fun too.
Whichever non-restricted PCC is used the numbers should be somewhat similar I think. Handy little things these carbines! Barfman's Ruger with lightweight Magpul stock (room for 2 or 3 Glock mags in there I think) seems very handy indeed for stowing as one piece with optic in place, very quick to put together. Though I don't doubt his shooting AT ALL (stood beside Mike too many times and watched him nail tiny things with an airgun at good distances with ease), my guess is that his trouble at 200 metres ("it's just not happening") might have at least something to do with using a dot sight, not a scope. I opted for the TNW primarily because I like the relatively long separation between indexing points on the barrel, about 9cm between the chambered portion and the flange held in by the barrel nut, which at least in theory makes for excellent zero retention between assemblies. If I ever really want to deliver ~250fpe at 150 yards, the 7x scope will come in handy for that, as will the numbers from Chairgun and Strelok, and any experience I build to further refine that data.