All good ideas.
I would check alignment again. Should have checked that immediately before you shot it.
SIG 220grn subs have always shot exceptionally well for me, but any company can make a mistake now and then.
I hadn’t shot it since I checked it the first time and I didn’t bring alignment rods with me to the range.
As far as the ammo, I haven’t shot it before but I figured it had to be decent. Sig gets so critiqued on everything, if it was junk ammo, I’m sure we would have heard.