I have the InvestArms Hawkens version made for both Lyman and Cabela's.
Cabela's .54 Cal:
Lyman's .50 Cal
Not sure but I always thought the Deerstalker was a less expensive version of the Hawkens. May be wrong.
Love the double trigger, and they work extremely well. Hope you can be able to swap out the single for a double set trigger!!