Recoil spring question

I have STI trojan in 38 super. I bought this gun slightly used so I am not sure what spring came with it. The pistol ejects brass quite a distance maybe 10 feet or so. I don't load them too hot 124 grain to about 1100 fps. About 4.2 grains of an Australian powder called ap50.

My question is does the pistol flinging brass that far have anything to do with recoil spring weight? Specifically is it too light? I have put maybe 7-8 thousand rounds through it and just does not skip a beat. What is a good weight for this pistol in this calibre?

This is a purely a target sport shooting pistol if it matters.