Roger, I'm now less confused. Stick with the 6" Harris. It's less likely to snag and extends to 9" if required. I'm using the BRM-S. Register at Brownell's and get a military armorer account - they have the best prices. While you're at it get the AR-15/M16 specialty catalog. It's almost as good as an encyclopedia. Things like the Grip pod are getting a "gadget" reputation. HTH
ETA: LaRue is offering combos - Harris bipod and their adaptor for good prices. One stop shopping.
http://www.laruetactical.com/
FWIW