The bore buttons made of felt have a good consistency in the load column, compressability is very little and I have seen them used for both bullet and ball with good success...
As with the thoughts about protecting the powder charge, I found several years back that I was using entirely too much lube and the amount of lube required was really surprising...So I did some experimenting...My bore butter would leave a build up in the barrel after several shots and complicate the fouling when shooting long strings of shots...I cured this by melting some in a double boiler and then adding it to some patch material in a plastic bag, making sure that it covered completely...then I take and heat the patching up in a small over or microwave (Low Temperatures) and then pat it as dry as I could get it...It feels realitively dry until you apply pressure between your fingers...This is the same process that happens whenthe projectile is shot out of the barrel the lube comes out under presuure, just like wringing a rag out...
I have left my rifle loaded like this for as high as 4 days with no problems...The more, what I call Greasy Kids stuff you use the more fouling problems you have...Recently I have shot up to 70 times without cleaning with no problems, this is due to changing my lubes around and not using as much...
Cutting in the bore with large charges is really relative to bore condition and tightness of the gas seal, patch and ball combination...One of my 62 Cal Bullet rifles, I use 120 2F to drive a 900 grain bullet at about 1300 FPS...In my 58 Flinter the sweet load is between 100 and 140 grains of powder, due to the 1-72" twist, and unfortunately as the bore increases and twist slows down, charges go up accordingly to stabilize the ball or projectile
Well I end it there, sorry for being so long winded, Thanks for reading my thoughts and opinions...
Hilljack