All of my rifles load and shoot as you note, Skychief, including the .32 and my 2, .58's, a double rifle and musketoon. That is, they shoot 1" or better at 50 yards off a frong rest bag. I don't use a rear bag with the ML's.
I don't need a mallet for any of them. I see the chunk and BR shooters using mallets - never had to use one.
The .40 I shot last Sunday, uses a .397"X .398" pure lead ball and .022" railroad mattress thicking patch. Actually, the patch measures (Taylor ws present) .019" with mic, .021" with one set of calipers and .025" with the other that was handy - so I called it .022". Stuff feels as heavy as 12oz denim, but is as soft as can be. Once started, which is easy - can be pressed into the bore with the stud on the starter- yet goes down with 2 fingers on the rod. That rifle does 1/2" for 5 shots at 50 yards. Few weeks ago, I used it with the .400" X .400" balls and it loaded virtually identically, with .0215" plain mattress ticking. Water/alcohol/neetsfoot oil lube. Oh yeah - the bore of this rifle is .398" and has a shallow angled, slightly less than 3/16" long cone at the muzzle.
Taylor's .40 and .50 that he uses on the trail, load just as easily with similar combinations.
The recovered patches are reusable, over and over- if desired - & no brown scorch marks from minor blowby in the grooves. With some loads and smaller balls, ie: .005" to .010" smaller than the bore, brown scorch marks can show in the material from minor blowby in the grooves, yet the loads shoot just as cleanly, even though they are a bit looser. Loading seems the same to me. I find a load that shows no brown or tannish scorch marks, usually shoots more accurately.
Isn't muslin a soft, rather open weave,thick fiber cloth? I had a .50 cal Bauska barrel back in the late 70's that shot some of that type of material amazingly well, but I had difficulty finding more of it. It would make a cloverleaf at 50 yards with the first 3 shots, then make the cloverleaf merely a round hole with the next two shots. My current .40 Goodioen and .45GM barrels do this with the patches noted above.