The Blackhawk is a real nice bipod. I have them on all of my rifles. I replaced the previous Walmart version which did not nave the tilt feature. It's a good investment if you're looking for a good, strong usable bipod.
Why pay as much as $100 or more for a Harris if you're not a competition shooter? The Blackhawk works as well for the average shooter / hunter.
You shouldnt need the adapter. Have found the knockoffs bipods to work just as well as the Harris on sporter weight rifles but still prefer the Harris for varmint barreled guns.
Just make sure it swivels!