I have been using Cr10 since finding Sweets became a problem in my area and haven't had any issues. Then again I have never left it in my bore for 15 minutes either. I pretty much subscribe to the "elbow grease method". Push the wet patch wait a couple minutes, push another wet patch wait a couple minutes, follow that with a couple of dry patchs and repeat until I stop pulling blue. I also start with my shooters choice solevant and then go to my Cr10 treatment.