I used to run a Harris on my AR-15 and my 15-22, but that required swapping the MIL-STD-1913 sling adapter between them at the range, which was a pain. Also, I had to remove it whenever I wanted to shoot standing, kneeling, etc.
This proved a much simpler supported bench-shooting solution:

Caldwell Rock Jr. Rifle Front Shooting Rest

(It didn't hurt that I got it on sale for $19.99)