RE: Clean barrel/dirty barrel
From what I understand many target shooters shoot a fouling round or two before actually competing. At least that is what I hear.
I know with my remington muzzle loader I shoot just about every shot from a clean barrel. I'm more worried about where that first shot is going to go since you don't get too many chances at a follow up shot with this kind of gun. It shoots pretty close any way though. But when I am sighting it in I clean the barrel and let it cool between shots. It is time consuming, but worth it to me. Especially considering I have a range of up to 150 yards where I hunt and I sight it in at 130 yards.
I don't beleive cleaing the barrel is as big of an issue any more with the newer cleaner powders. I mean I wouldn't leave it scummy all the time. But I don't think shooting it and leaving it sit would actually hurt the barrel any. I'm talking rimfire and centerfire here, not muzzle loaders. With an ML it would depend on the type of powder you are using. I don't clean my .22's or my .17 every time I shoot them and I have had no problems with them yet. You do want to get the lead and copper fouling out of them, so I'm not saying never clean them. Just that from what I can see the newer powders and primers at not corrisive and it doesn't hurt the barrel any. Now if you are shooting some kind of cheap army surplus crap with corrosive primers or something I would clean after every session. I don't think it a big issue with premium ammo though.
The only way to really know would be to try it though. Keep in mind heat may effect it as well.
I'm not a gunsmith or a target shooter either, so I may be full of crap.
Paul