I brought my 2 brand new 9mm shields out today for their inaugural break in. I started with about 60-70 rounds of federal fmj red box stuff thru each. Not a hiccup from either. Grouping was at my poa at 7 yards. Then I switched to the sig jhp's I picked up on sale at Cabelas. I ran about 15 rounds thru each gun. All cycled properly. However, the poi on both guns was 3-4" low from my poa. Just to be sure I wasnt doing something different, I switched back to the red box fmj. Poi roughly the same as poa. Back to sig jhp's-poi again 3-4" low.
Anyone have similar results from this ammo out of subcompacts?

I've made my own 115 plated loads to match my 150 HST carry ammo.

The Shield's rifling makes 147's in any flavor better accuracy-wise. Try 147 Sig V-Crowns and get back to with the results