Spray gun reservoir with oversize, fast-fill opening

A liquid supply assembly for use with spraying apparatus such as a spray gun comprising a reservoir for a liquid to be sprayed, the reservoir having a first end, a second end spaced from the first end, an end wall at the first end, a side wall extending from the end wall to the second end, the end wall having a spout providing a fluid outlet communicating with the reservoir, wherein the spout is connectable to a spray gun for connecting the reservoir to a fluid inlet of the spray gun characterised in that the spout is provided by a cap member releasbly secured to the reservoir around an opening in the end wall, wherein a marginal edge of the opening is spaced inwardly from the side wall at the first end, and the reservoir can be detached from the cap member for adding fluid to the reservoir through the opening in the end wall.