I know this is an old thread, but I thought my Red Wolf experience might be relevant to the OP and some of the respondents. I have a standard power RW in .22. As received, it would shoot a good group, then maybe a lousy one. Unexplained flyers continued during the course of eliminating all the usual variables one might suspect. Finally, there was nothing left except the barrel. I described the symptoms and my trouble shooting to the folks at AOA, and they agreed that the barrel was the likely issue. They sent me new barrel, and it immediately shot great, and continues to do so. In fact, it shoots as well as my RAW and Steyr. I sent the original barrel to a tuner who is well known to many AGN members, and the original barrel was scoped and found to have a couple of burrs in the chamber and port opening, so pellets were probably being damaged when loading. I will mention another thing that could be related, although not proven. The original barrel was one with an air stripper that screws on the threaded muzzle. The replacement barrel is not threaded, its stripper simply slides onto the muzzle and attaches with a grub screw. The AOA folks mentioned that some barrels of that generation were found to be problematic. Threading the muzzle of a barrel is a longstanding and much debated topic, and I do not claim to know the answer, as I'm neither a machinist or metallurgist. But, I believe it has been proven that threading the muzzle can alter the internal bore dimensions. So, if you are having accuracy issues with a RW, don't overlook the most critical component, the barrel.
To the OP, you mentioned a strange sound and vibration upon firing. You probably know by now, that is the normal firing cycle of the rifle. Since you don't have a spring and hammer slamming around in there, the sensation is different, but what you heard and felt is likely normal.