Originally Posted by
Urban_Redneck
My guess is that it is some of the protectant that TC applies to the bore before shipping. With the rifle in a vise, a good scrubbing with a new brush will get you clean as a whistle.
The Otis system is handy, but, will not get you there.
YMMV
Not sure why you think that is the issue. Why would the protectant be clinging to only ONE rifling groove, from breech to muzzle?
I can get my guns cleaner with Otis than with a ram rod any day. If anything, a cleaning rod is handier and faster to use than Otis.