Have a more experienced pistol shooter shoot the gun. Then have that same more experienced pistol shooter watch you shoot the gun. More than likely the more experienced shooter will shoot better groups more like 3" @ 15 yards or less and will have some insight as to how you can tighten your groups.
Without watching you shoot the pistol it is hard to give real meaningful advice. IMHO it is not the "arrow" it is the Indian. Changing ammo is putting the cart before the horse.
You need to look at your grip, stance, sight picture, trigger pull etc. Once all of those are worked out and are rock solid then you can blame the ammo.
I personally am not at that point..... LOL
I would start with your grip and stance. Check out this video and see if it helps.
https://www.youtube.com/watch?v=ysa50-plo48