I am probably in the minority here in that 147gr (either Federal Syntech TSJ or Magtech FMJ) seem to be more slightly more accurate in both my PC Carbine and my FX9. However, once in a blue moon I seem to get the FTE in my FX9, but we're talking once every two years maybe.
My PC Carbine seems to perform fine with 124gr as well (again Syntech TSJ, S&B, Federal AE, Winchester WW, CCI Blazer, etc.). It is not as accurate as the 147s - I don't know why.
As for 115gr, I know everyone uses the term "snappy" with them, but I really don't notice a difference in using them on my PC Carbine (aluminum handguard, adjustable stock model) between 115 and 124 - not sure if it's because I hang all sorts of accessories like flashlights, magnifier, angled foregrips, etc. off of it increasing what is already a more front heavy carbine, but 115 seems ok.
All the above that I have used are brass cased, not aluminum.
The only thing I will say is that the PC Carbine with some kinds of defensive ammo, seem to not play well, but due to cost, it hasn't been a huge sample size (maybe 20-40 rounds) - some feed issues particularly. Could be the mag too, I don't know (Glock magwell, Glock, PMAG, and ProMags). And regardless of ammo, the last round bolt hold open with the Glock mags and magwell are not reliable at all, compared to using a Ruger magwell and a Ruger mag.