I picked up some Pearce grip extensions for my R9s after reading that other forum members had modified the Kahr model to fit the R9.
I wasn’t pleased with the fit, as it seemed loose. I tried to remove the extension to see if it would stay put and was unable to remove it. I inserted the magazine into the pistol and noticed a different gap between the end of the grip and the top of the extension compared to the factory magazine. I was worried that the Pearce extension would slide off as I could remove it when the magazine was in the pistol.
I made a brass shim that would hold the Pearce extension tighter to the magazine. The shim significantly tightened the fit of the extension to the magazine and allowed for a metal to metal fit between the extension and the internal magazine base plate.
After I was sure that it all fit together properly, I epoxied the shim to the Pearce extension. It was already a very tight fit, but I wanted the shim to become part of the Pearce extension.
Pictures are of factory magazine; unaltered Pearce extension magazine and shimmed Pearce extension magazine. I also show the parts and the shim installed into the Pearce extension.