Wanting to get a bipod for my 20" AR and have decided on Harris based off of multiple recommendations. Was just on their website and got lost, can't really tell the difference between the models. I've got the typical rail on my hamdguard, would prefer to mount it directly to that. Would like to be able to "swivel" and or twist the gun in order to move to a comfortable position to shoot. Recommendations? Wanna kill these ads? We can help!