One size does not fit all !!!
In inlines or any other front stuffer...
...finding the 'sweet spot' with an inline is the same as finding the 'sweet spot' with a side cocker or any other front stuffer. Just different components.
But once you find it(sweet spot) you will not regret it.
Your inline .45 is capable of some very accurate shooting at some very impressive distances.
As has been said, hate to see you throw the towel in so soon as with a very little tweaking with your choice in your sabot, your problem can easily be corrected.