I have a double action h and r 22 mag.. It misfires and is inacurate, i belive due to about .010 slack (slide) in the cylinder.. It was a 22/22mag interchangeable cylinder gun.. I think the cylinder, when back, slides forward on fireing keeping the hammer from fully impacting the .22 rim thus a misfire... What im asking is shimming an option here, and could it improve accuracy.. The shell can slide back giving a .010 difference in bullet jump, and of course the cylynder is in different possitions on fireing.. The barrel i belive is capable of 2-2 1/2 inch groups and would be acceptable.. but its getting 4-5 inch groups .. thanks dave