So, who do you propose provide the "hard answer"? I posted what I found out on the TC rifle forum and was told how stupid I was.
The fact is that the "hard answer" is not the popular answer, so it will always be disputed by those who don't want to believe it. The "hard answer" can be found out by reading the US Supreme Court decision that can easily be googled and read. It discusses going from a pistol to a rifle, but not the other direction. It is also a decision on a Contender, not an Encore.
I choose to go from Pistol to Rifle, not the other way around. That way I have case law that is on my side. While you may (most likely) will be safe the other way there is no case law to support the legality. Should you become the test case you are in for the hassle of a lifetime.
You will need to decide what you want to do. And if you would like a legal opinion then best get it from a lawyer, not the internet.
Good luck, whatever you decide to do.