Cr5, what barrel profile is on your AR? Because that will matter.
I have owned a few AR's and have been shooting the C7 in service for a long time. Any govt profile 20" barrel will be affected by handguard and barrel pressure. If we are talking about H-Bar's the effect will be less.
I dont know how you were loading that rifle but If you could not shoot your rifle accurately don't blame the equipment. Before your rifle left the factory it had to group 10 rounds at 300m or it does not go to market.
Bipod use has been covered enough regarding these rifles, only the 300m target community uses it and they load it the exact same every time at a range, I have shot in Switzerland. The military guys do not use that bipod to shoot for the same reason I don't clip a bipod to the front of a C7, my accuracy will go to sh!t
As for the receiver flex comment regarding stamped receivers, Heckler & Koch made the G3, HK33, MP5 and others the same way, the receivers do not flex and are very solid.