Brian,
I'm no expert, but I wanted to put my new books to use! I checked RCA 1 and 2 and Kindig's "Thoughts" and none of the guns shown that are signed by or attributed to J.P. Beck have double set triggers. One rifle, RCA #98, does have a single set trigger. It is gently curved with no curly decoration on the end.
The J.P. Beck rifle shown in the ALR Virtual Library also seems to have a regular trigger.
Hopefully others with additional references will chime in.
-Ron