Dusty Stevens
Hollow Point Dispenser
Post some pics of that rubber. If its that drawer liner stuff itll make big groups. All bags need some type of slick-um. Gotta break the bond as quick as possible upon recoil. Use baby powder or bag wax on leather or powder or silicone spray on cordura. Ive even seen some use dryer sheets in the past. Make it as slick as possible with no rocking. Sliding your gun back n forth the dot should come back to the same spot on your target and after recoil should return back verrry close. If not you need to find out why and fix it. The name of the game is fast and having to adjust much between shots equals slow.