Our 40 Caliber.10mm patch jag is designed specifically for cleaning .40 caliber barrels, including but not limited to 40S&W, 10mm, 41 mag, 400 Corbon 41 Action Express. These patch jags press a patch that has been treated with solvent or bore paste against the barrel and into the rifling to mechanically strip the carbon, plastic, and copper out of the bore. We used this patch with no solvent for demonstration purposes, and pushed it through the barrel once. As you can see, these Jags clean better than any other jag on the market. “The proof is on the patch”. In addition to cleaning, our jags are also used for oiling the bore for storage as well as removing oil before firing. Our rifle jags fit all rods with standard 8×32 threads. In addition to this product, we suggest you purchase USP Bore Paste and round TCS patches for .30-.45 caliber rfiles and pistols. TCS round patches are the perfect size for use with this jag, and other patches may cause fit problems. Square patches should not be used with our jags.