Like they said. It's a fixed internal magazine where the bottom floor plate opens out like a small door. So, imagine the floor plate of a detachable magazine except that floor plate has a hinge at the front end where the plate opens out, but the magazine does not detatch, the magazine spring and follower are also attatched to that floor plate. On the 700 BDL the floorplate release is a flush square button in the trigger guard just forward of the top of the trigger.
A word of advise with that 700 BDL. Don't allow the bolt to slam forward on it's own. It will easily do that when the action is open and the rifle is pointed muzzle down. Also the 700 BDL will need to be fitted with a much better aftermarket rubber recoil butt pad. Consider a Pachmayr butt stock recoil pad. For some odd reason Remington has found it cheaper for them to put a basic hard plastic butt plate on that gun, and those tend to really make shooting it (in a caliber like .30-06) very uncomfortable. Hope this helps.
Anyone who shoots a sabot bullet has had the problem with loading the next round with a dirty barrel we have all struggled with it.
Between muzzleloader shots I have done some research and testing on my own to find out what works for me for the next shot. I have been using a product called bore butter and when the muzzleloader is just sitting around I leave it caked in the barrel for protection. Have also found that if I lube my sabots with bore butter they really slide nicely down the barrel....