I also just got a .25 cal Kodiak also made in England. Mine was used but was also professionally tuned when the previous owner had it. Its such a sweet shooter. I haven't had the chance to shoot it past 10m yet but I'm getting very good accuracy. I hope that holds up at 25m and beyond. The workmanship on the rifle is beautiful. I'm not one to care about aesthetics of a rifle but this one is definitely the nicest looking rifle I have.
Of course, I need more range time with my rifle but yesterday I already started trying to shoot off-hand and surprisingly got a good 10 shot group at 10m. I say surprisingly because I have very little practice with off-hand shooting. I don't find my rifle to be very hold sensitive. Also, I'm shooting open sights since I don't have a scope mount for it yet. I've been chrony testing it but I don't have my figures with me. However, I believe I was getting about 800fps with 20gr H&N FTT pellets. Most of the 25 - 30 gr pellets were in the 650 - 750 fps range. This rifle is definitely for hunting.
I haven't opened up the rifle to see if it has a spring or gas piston in it. However, it cocks and shoots so smoothly. There's no buzz at all but it has been tuned. I'm curious to see what's in there.
One thing I have to add is that most pellets seemed to fit a wee bit loosely in the breech. I don't know if I'm just used to overly tight breeches or if the rifle's bore is a bit big. I'll eventually see how the accuracy is when I get a chance to shoot at longer range.