With the barrel screwed in the magazine needed attention as it needed to be single stack to work with the larger front of the cartridge compared to the 303. I took the 22 LR as an example of the shape needed to successfully hold the cases at the proper angle and to release with bolt travel at the right time.
A section from an old vehicle roof rack would serve as a follower and while I havent shown it I needed to sit a wedge between the base of the mag insert (riveted to the mag through the drain hole) and the spring base to sit the rear of the cartridge up high enough to give correct orientation for delivery into the chamber.
