In my limited experience the palm grip is less common than the cast AL hand-stop.
https://freelandssports.com/product/freeland-fscv-hand-stop/ or:
https://freelandssports.com/product/anschutz-4751-adjustable-handstop-w-sling-swivel/
Can buy the t-slot rail as a blank and inlet it into the forearm:
The Anschutz aluminum rail section is designed for Anschutz type accessories used on many European target rifles. The rail is blank and unmodified so you can put marks or screw holes anywhere you want or cut it down to what ever size you need or leave it 15" long.
freelandssports.com
I did exactly that on my latest project so that I could easily swap out a bag rider for a bi-pod stud or mount, pictinny rail section, or anything else that I might decide that I want at some point in the future.
The new bench rest block adapter attaches firmly to the Anschutz rail on the bottom of your rifle to give you a flat square profile perfect for bench rest stands. Block is made out of a high strength synthetic material ½”x3”x6”
freelandssports.com