Are you saying that the same ammo brand, type, and load is moving it’s groups? Or are you saying each type / brand of ammo is grouping differently? The second situation is not uncommon as each load behaves differently due to powder and bullet differences resulting in speed variations etc. If the first is true I’d look for something loose on the gun (barrel/scope) or at shooting technique. Are you resting the barrel on something? Are you loading the bipod the same, same grip, same body position etc.