Try this , gently scrub the flutes :
0000 steel or copper wool and Ed's Red Bore Cleaner.
Ed's Red Bore Cleaner - Equal Parts:
1.) GM Automatic Transmission Fluid - standard , non-synthetic type
2.) Acetone
3.) K-1 Kerosene
4.) Mineral Spirits (deoderized)
Store Ed's Red in a metal can with screw on top ...or in a clean Windex spray bottle ... the mixed cleaner will not dissolve Windex spray bottles ... other bottles , I don't know .
Ed's Red is a good general purpose cleaner for shop tools and firearms .
I use it as much as a general cleaner of shop tools & equipment as I do a Bore Cleaner .
It cuts through layers of built up grease and grime .
$22 will buy the 4 ingredients at wally-mart to make a Gallon of cleaner ! Warning ... do not use synthetic ATF , it will not blend and mix with the other 3 ingredients ... Use Conventional ATF !
Gary