I put the Saber Tactical Arca rail on my M3 and went with the Accu-Tac FC-4 G2 Bipod. It's got a wide stance and is rock solid. However......
I rarely use a bipod anymore now that I've gone to a little carbon fiber tripod and ball swivel mount.
And you can get that setup for half the price of an Accu-Tac bipod.