FWIW - I used to shoot a lot of registered trap. I shot the enough to have to remove plastic buildup as well as other grime. I found the most effective method of cleaning the barrel of both an 870TB and 1100T (early 1980's guns) to be a Hoppes tornado brush. I have used the a tornado brush on these two guns for more than 20 years. No signs of any ill effects. I have put at least 75,000 shells through the 870 and 20,000 through the 1100.