Tracker is correct about the comparability of reading primer strikes and tea leaves. In addition to the variability of primer hardness among (and even within) brands of ammunition, cartridges loaded to higher pressures can result in the primer's being flattened and even extruded back into the firing pin hole from the ignition force, as Corey has noted.
Since 124-grain Remington Golden Sabers come in both standard and +P loads, it is just possible that you had a box that was not correctly labeled. (Such happened to me once with another brand in .380 ACP.) In any event, since your R9 is producing obviously satisfactory results with the 124-grain Speer Gold Dots, it would seem that you have found your carry round.
Good luck.
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And lest I forget, welcome to the Forum!