If you're handy enough, to replace a 10/22 internal trigger group hammer, it's not a stretch to take out the .44's hammer & rework it.
A light polishing of the sear face and pivot pin & it's hole in the hammer, plus maybe a small lightening hole drilled transversly through the hammer ought to do the trick.
If you decide to try it, don't neglect to polish the tips of the mainspring and all of any attaching/rubbing parts.
I'd buy a hammer from a parts dealer, and rework it first. Then, if it came out OK, a switch-out is all that's needed.
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