HDW - Don't have one in 454 but here is a review from someone who tested one and published the results on the net. He notes .45 LC as being used and reports no issues with it. Also states how the mag. tube has a re-designed feeding/tension system, for what it is worth:
http://www.gunblast.com/Paco_Legacy_454.htm

I have one under the old Rossi name in .357 and it is neat little gun. I have fired .38's and .357's in it without a problem. Good luck, hope someone can step up and speak with actual experience for you.