I purchased a Christensen MPR and have been mostly happy with the gun overall but the rear is awful on a bag. Christensen makes a pic rail just for the rear of the chassis for mono pod attachment. The spacing is such that a standard pic rail hole spacing doesn’t fit, so you have to buy theirs. I wasn’t able to find a simple bag rider for this chassis anywhere on the Internet. Fortunately my buddy owns a machine shop and a 3D printer. I sent him over some dimensions and now I’ve got a direct fit bag rider. For anyone that has a MPR chassis and may be interested in one of their own I can provide contact info. I’m sure he is able to CNC one out of aluminum as well. Either way I’m happy to have a simple and effective solution to an overlooked detail by Christensen.