The 1931 Small Arms Training describes Snapshooting as:

When instead of firing a shot deliberately as in slow fire, it is necessary to fire one or more shots as quickly as possible, such fire will be known as snap shooting or rapid firing… The essence of snapshooting lies in the ability to take the regulation aim rapidly and accurately, and to release the trigger at the right moment without disturbing the accuracy of the aim.

This obviously needed a lot of practice and a small cardboard target was used at 100 yards and a larger target for 200 or 300 yard practice. This target was made of pasteboard and shaped rather like a lollipop:

The top half of the target is printed with two circles and a black semi-circle to allow it to show up against different backgrounds:

The target’s designation is printed on it, along with the ranges for different types of range:

The 200 and 100 yard distances are for .303 ammunition and the 25 yards for .22:

The Small Arms Mannual explains how training could be undertaken:

Squad will be practised first at large snapshooting targets at 300 yards, and later at sihouette targets at ranges varying between 100 and 300 yards. The length of the exposures should gradually be reduced from five seconds to three seconds as progress is made. Targets will be exposed from different places. Occasionally men will be practised in having to fire a second shot immediately after the first one. For this purpose two exposures in very rapid succession will be given.