I just use a pic rail because that’s the interface my rugged ridge bipod uses. The pic rail works just fine with the RRS head and for me I think the 40 is about right. Beefy enough it stabilizes the rifle no problem but I don’t need the extra weight of the 55 head.Appreciate the review sir. Which arca attachment did you use with the MDT chassis? Been debating a similar setup and have found SRS and Area 419. Did you feel the BH-40 was right for your setup? I know the make other sizes big and small.