Thank you for your response.
The Ruger attachment won't work with a aluminum handguard that the lr 308 has.
I did find a Pic Rail adapter from Caldwell, item 156716 that looked like it would work.
I ordered one, and just installed it. Installation was very easy, very tight, with zero play.
So, when the new bipod arrives, I will test it. I have several Harris bipods, but I feel that
they are too lightweight for a 13# .308 AR10.