You don't need to take the breech plug out after each shot, when they say to loosen it after a few shots when using triple 7 powder it's because it will end up having so much crap in there so that you can't take the plug out at the end of the day. If you loosen a half or whole turn every 5 shots or a bit more, and then at the end of the shooting session, just taking the plug out before you go home there shouldn't be any problems. A good lube on the threads always helps too. Some like tc thread lube, but I've always had pretty good luck with gorilla grease(a purple color lube, that comes in a half dollar sized container). The powder should be all burned out just after you shoot, I think the whole thing about burning embers comes from the old field artillery pieces. If it was me though, I would wait about half a minute- a minute after each shot. Sometimes, I will blow air through the barrel too, just to be sure, but it's not really needed. I have been looking lately at those .458 and .475(the ones for 480 ruger bullet) sabots. I might end up trying some in the future, but the .452 ones work really good. As a general rule, the closer to the size of the bore you can get your bullet, the more accurate you will be(i.e. 452 as opposed to .429, etc...), there are always exceptions though, as some people can drive tacks with .429 sabots. Powerbelts are another option to try if you want. I gave up on them because I like to shoot, and boy are they expensive!
~~Amos