[1] At the time target rifle competition in the UK was dominated by designs based on military actions such as those of the Lee–Enfield and Mauser 1898.

These designs were felt to have reached the limits of their development potential; especially when combined with commercially manufactured or hand-loaded ammunition.

Swenson had been employed by the London gunmaker John Wilkes of Beak Street and whilst with them had commissioned the manufacture of a 'Universal' target sight and a copy of the Finnish Mantari match trigger.

This, combined with a firing action ("lock time") that was measured at less than 1.7 milliseconds, was a significant feature in its early success.

The position of the lugs, at 45 degrees when closed, was suggested to be a compromise between the compensation characteristics of the Mauser and Lee–Enfield types of action with the former locking vertically and the latter horizontally.

In the 1986 documentary "Bisley The Queen's Prize", while reviewing the complete history of winning rifles of the competition, what is purported to be a SIN 71 M5 is fired around the 31 minute and 45 second mark.