The 444 Marlin was a factory chambering.
They are out there but most won't sell theirs.
As for the 405, yes, it has and is being done now.
I know that Tim, (Quickdtoo) here on the site has one.
Not sure what he used to start with.
I am having one done right now on a 28" 38-55 Target Classic.
Should be done in a few weeks.
The style of the Encore stocks don't lend themselves to well to the heavy kickers.
I have a 405 Encore and it shoots great but does have some recoil.
I prefer my heavy hitters on an H&R Frame/Stock set up.
Just seems to fit me better than an Encore.
Here is what mine will look like when its done.
LONGTOM