I started my .577 Musketoon off with .575" RB's and a 10 ounce denim patch - that's .0225" thick. That particular Enfield's bore diameter measures .574", with grooves only .003" deep at the muzzle, .011" deep at the breach. A .575" ball would just sit on the crown - by itself. It's .003" deep muzzle rifling makes it .580" groove diameter at the muzzle where that .575" + .0225 + .0225" combination had to fit before it could be pushed down. Yeah - it was snug due to the .620" combination being introduced into the .580" groove diameter (.020" compression per side).
As soon as I could pick up a .562" ball mould, I did - however I did shoot that .575" ball and thick patch on the trail 2 weeks in a row - using a 'good' short starter then the rifle's short steel rod to push it down. Once inside the muzzle, it went down easily, as it was then sized to the bore and grooves. No - the patch did not cut, nor did it burn - fired patches were resusable.
With the .562" ball, I use the thicker red/white/blue/blue railroad mattress ticking that runs .023". That combination still measures out at .608 - still nice and snug with .028" compression - .014" per compression per side in the bottom of the grooves.
What is needed to load tight combinations?
Technique and a good muzzle crown.
Your rifle, especially if a production rifle and not already altered by someone, did not come with a good enough crown. It will not allow tight combinations without ridging the ball's metal or/or cutting the patch material if snug combinations are attempted.
Anything less than about an .018" tightly compressed denim or ticking patch is not even useful as a snot rag, in my most humble opinion.(or the most humble opinion I can conjure up on this subject).
I'm not alone, here guys - Taylor, LB, Wade P. Neil H. Big Ron, Darrell, Kim, my Wife and Daughter - and many others here also shoot tight combinations - why - because they are accurate and never need wiping while shooting and STILL are easy to load - -remember - technique and muzzle crown.
If your bore builds fouling, then, as Taylor said - it is pitted - or you are not using enough lube - licking a patch does not constitute a spit lubed patch - or your ball and patch combination is too small in diameter - or a combination of any of these "problems".
There are a lot of "accuracy" shooters right here at ALR - NONE of them use thin patches and undersized balls - if they did, they would not be included in the group of accuracy shooters - think about it.
If you're happy with having to wipe your bore because you don't want to, or are unable to load a tighter combination and you are happy with what many might consider poor accuracy, that's just fine - but please don't say it's impossible to load tight combinations without a hammer or mallet - that just ain't so. If a bore sized ball (let alone .005" undersized) and .020" or a bit thicker won't go in - your crown or technique needs work. Pure and simple.
A .005" 'under' ball is where we start now in all rifles - automatically, with that 10 ounce denim .022") patch. We find it works in ever rifle - we only need to find the powder charge it prefers and the 'working up a load is done' - It does not matter if they have .016" rifling, .012" or only .004".
My first Ml rifle, a TC, with it's typical wonky tight/loose/tight/loose/tight/etc - buttoned .004" rifling and 48" twist worked best with a .495" ball and .022" (compressed) denim patch & 80gr. 2F C&H - and that was 40 years ago when I was a kid and when I first started learning this game. I did not have to wipe that rifle while shooting - it shot 'clean'. I followed Ned Robert's teachings that, as he wrote the Dutchman said "Ven yu loads der next von, yu cleans der last von (and the last load of the day, loads as easily as the second).
Today, I find the last one loads as easily as the first - or when shooting my .32 longrifle, it loads more easily than the first if using track's Mink oil (or Neetsfoot oil) for lube. That is using either a .311" (my first mould), or the .320" ball that I use now (doesn't matter much) and .0230" ticking patch in it. That rifle has .008" rifling- but a beautiful crown- of course. In this rifle, I found the small ball would not shoot well beyond about 38gr. of 3F, while the larger .320" ball shoots well with up to 45gr. - interesting - 45gr. gives me just over 2,000fps.