Spring only, will upload some data sheets when i find them!It should also get a little quieter as the crud begins to disappear. I have always favoured a rod with a solvent on a brush followed by a jag on a rod to push some cleaning patches through the barrel for initial cleaning of the grooves. I see bore snakes as being great for out in the field if you need to give the bore a quick wipe but they're not up to cleaning out stubborn stuff.
I'm having trouble finding any proper data on the stoeger Fx20 combo's muzzle energy. It gives all the data in M/s without giving the grain weight of the pellet. There is plenty of info about the model 3S's built in suppressor which looks very cool. Can you tell me if your version is spring plus nitro piston or just spring powered?