My 39AS is not exactly an older gun, as it is only a few years old -- and had less than forty or fifty rounds fired through it.

It' s clean as a whistle inside, as the gun shop guru thought the same thing (carbond buildup, dirt, etc.). We broke it down right there, and the only suggestion he had was it needed some more lubrication. He was miffed by the fact that CCI ammo misfired through it, but also said he' s seen a lot of this " finickiness," as he called it, in the 39AS. Must not be as reliable as the 39A, since you' ve never experienced any problems with yours.