TC4ME
I almost hate to mention this because it is going to start up a huge discussion again.... I shoot sabots exclusivly in 6 different ML guns and 4 different shot guns - 2 of them high quality trap guns. I do not get plastic fouling in any of the ML's and I now can also I have reduced to plastic fouling in my shotgun chokes drastically. OK here is the dirty word "bore butter"
I believe if it applied in what i think is the correct method it really reduces fouling.... Example if you have a shot gun with screw chokes after you have shot several rounds through the choke take the choke out and look at it. It will black and streaky with plasic fouling - put a little BB on your finger and rub it around in the choke - you will really be surprised.
How the bore butter is applied is the real key - It should not be caked inside the barrel or added to the sabots as a lubricant, nor should it be used as a spitpatch.
The ONLY time I use BB is in a HOT barrel after cleaning and when the the barrel is dry. Apply BB to a cotton bore swab and run it down the barrel, the hotter the barrel the better, because the pores are wide open. When you pull the bore swab out you will not belive what has happen, the pores in the barrel will litterally suck up the BB completely remove it from you brush. I do this a couple of times - then while the barrel is still warm dry patch it with a clean patch and get as much of the loose BB out as you can. After it has cooled repete the patch process. The only BB that reamins will be in the pores and a smal amount trapped behind the rings. Your first shot will remove that also. What you have now is a clean and smooth barrel, I really hesitate to use the word "seasoned" because it is not what is smooth less prone to cause fricton and this coating last for several rounds releasing a bit each time til it is all gone.
Lots of people are going to disagree but that is what 6 years of experiance has shown me and others. It is all in how you APPLY IT.
Another I do not battle and I think it is again becuse of BB - I do not get the "crud ring" in any of my ML's and I use t7 and with 209 ignition. When I patch the ring justs melt away if it is there.
Now, all of this is my opinion and you results may not be the same - BUT don't shoot the messenger - the non BB folks are a lot more vocal than the BB users.