That's the BEAUTY of trying another brand of .22 rimfire ammunition, to eliminate the possibility of the "eagle brand" being at fault and not operating well in your pistol. :roll: There's no sense in swapping out parts until you target the issue and what might be causing any failures. That's just basic Gunsmithing 101. Do the obvious thing first.
If you can get your hands on some CCI Mini-Mags, those normally work very well in new Ruger Mark pistols. When you mention "eagle brand", my thought was maybe you were trying some of the American Eagle "Suppressor" variety, at around 920 FPS. Those may not work well in a ~NEW~ pistol until the springs develop "set" and reach their working lengths. Once you get several hundred rounds through your Ruger pistol, these guns will digest just about any .22 rimfire, except for the hyper-velocity, which is NOT recommended by Ruger. Recently, I've even been working with CCI Quiet ammunition to get that stuff to feed & cycle in a 22/45, and am almost there.