With this adapter it is possible to securely mount a Harris bipod to these rifles without the bipod tilting upward.
First, insure that the rifle is empty.
Then install the spacer and bipod as shown.
Unscrew knurled knob on bipod so you can squeeze the clamping bar to open it wide enough to go over the bipod stud.
Once the clamping bar is over the stud, screw the knob down tight.