I have also used JB's for the last 30 years, no problems. I have seen others have issues with it from over use and not following the instructions (Mfr's usually do try to make their product look its' best by experimenting to find out what works best- it would be pretty dumb not to. Yes, I was in manufacturing).
Several years ago I was told by a custom airgunsmith he was concerned with JB's in some of the older/softer European barrels, so his alternative for lapping/cleaning was Maguire's Magwheel polish, which is a finer compound than JB's. I have not kept up on barrel material in use in 2015, but historically the metal has gotten better and better thru time. Hats off to the mfr's- they're doing a damn fine job, especially for production/semi-custom barrels.
I also use KROIL and am very satisfied with it. I use the included tube extension and insert the tube in my Marauders past the port, before spraying. I use a soda-straw to get the boresnake's weight past the moderator, boy was I glad someone pointed that out...
I use lubed pellets (Yarrah's method described previously by Ted in Madison (i think)) and pull a boresnake thru at the end of every tin when shooting in the field. I used the KROIL if accuracy drops off or about every 3 tins as a SOP. This last season was a slow one for me and I went thru about 3000 pellets. Single outings are usually 2-3 tins and sometimes more, having to stop because of air bottle depletion. I shoot squirrels with a vengeance and NO regrets- 21 square miles of hayfields worth- hate those hole diggin', hay munchin' bas#@%$s....
Good Luck & Good Shooting- Hi-vel
PS- Quality response AZUARO, good job.
ive never was concerned that the barrel would be damaged, its just not that rough. I like it and will continue to use it when a really good cleaning is in order.