re: If you could build the perfect deer rifle

The single shot XP-100 w/ a grip in the center (like this one) is based of a modified Remington Model 600 action (carbine), itself a modified Model 700 action. The dogleg bolt is unique to the XP-100 and the Model 600. At one time, Remington made a rear grip XP-100R, the R standing for repeater as it had an internal magazine. The XP-100R used a Model 7 action.
Wikipedia, XP-100