I know your asking mac, but I would look at the H&N range. I use FTT's in my twenty two, which are faultless to be honest and Barra Hunters in my 98. They are heavy mind, 10.6grn, and to be honest, I feel like I need to be on top form to get them to stack, however when they do, they properly do. Can beat good old H&N FFT's though. Do choose the head size well though, as the 4.52 are ultra tight fitting... Like finger bustin' tight.
Re the rifle, get it apart, clean it up, see what happens then. All will come good