JB's will not hurt your bore. Yes Yes I know .... but it's abrasive .... You will burn ... heat erode the throat out of your barrel long long before any harm can be done to your barrel by using JB's and I mean using JB's a lot. some of the most accurate rifles in the world are cleaned with JB's all the time. It flat amazes me how people will worry and worry about using a brush and very mild cleaning compounds ... I'd never do that to my rifle barrel or my favorite, "You can use it on button rifled barrels , but not on my cut barrel." But frequently these very same people ignore the effects of high pressure burning powder on the life of their barrels.
JB's and Flits are fine to use to maintain your barrel, I don't give a darn how it was made.
But then when you start talking about some of the other true lapping compounds, it's and entirely different story, you need to know what your doing with some of that stuff.
Byron - good question and I'm not being agrerssive towards you or your question. It just seems like much of this discussion is little more than old wives tails with little fact to back it up. I use both Flitz and JB's on my accuracy rifles. Not necessarily all the time, every third cleaning or so. Chemicals will clean most copper fouling, but some fouling simply needs something more agressive especially in the throat area where a layer of copper then carbon (from firing each round) then a layer of copper, then carbon, then copper .... etc. seems to build up to an almost ceramic like layer! You need more than chemicals to get the job done.