Rock Fish

You are exactly right... but the physics of the two are a lot different. Another thing and this is just my own personal opinion, the 'crud ring' may also be related to what is in the bore... The Temp and the Pressure are reacting and crystalizing with something. I have no idea what... All I know is for some reason I really feel no pain from shooting T7. I even shoot it with PRB's and it works well with very little residue left in the barrel.