Just for &^%$ and giggles last week after a range visit, I decided to use a chamber plug I'd nearly forgotten I had in my Howa 1500 .223 Rem while cleaning. Popped it in and let the barrel soak in Butch's for a bout 5 min., dumped it, brushed it well, and the first patch I ran through came out jet black! It took twice as many subsequent patches as usual to finally get one to come out clean, and many of those showed green from copper residue. Next day, the rifle (which has always been accurate for me) shot sub-MOA consistently at 100 yds. after about 10 rounds had been put through it. Do any of you use this process on your target rifles, and if so, how often? I can only assume that cleaning to this extent was overdue, as my "normal" routine never produced such results. Just wonderin'.