The Hotchkiss Universal is fairly complicated and was probably pretty expensive compared to SMGs of it's day, like the British STEN and American M3 Grease Gun, which were mostly made from bits of tubing welded together, and maybe a stamped steel grip frame, with a barrel screwed on the front.
The drum magazine of the WW1-era British Farquhar-Hill rifle doesn't have feedlips. The rounds are held in the magazine by a manual latch. The feedlips are machined into the receiver, sort of the way it was done with the Mosin Nagant. After loading the magazine, and releasing the catch on the magazine, the bolt is released by pulling the trigger, which makes it easy to put back into action, but somewhat dangerous for anyone who happens to be nearby, such as your brothers in arms in the trenches, as you are preparing for a run across no-mans-land.
According to the Wikipedia article, the standard drum held 20-rounds, but there were also 65-round drums. The .303 British cartridge, like most very-old rifle cartridges, is a rimmed round, which doesn't work very well in box magazines. The rim of the top round in the magazine can get "locked" behind the rim of the round under it. Drum magazines are a way to get around this, providing that you can made the drum magazine work properly. As far as I know, the SMLE box magazines worked fine, but at the time the Farquhar-Hill was designed, the SMLE magazines were all 10-round capacity. However, the year that that the Farquhar-Hill was adopted, there was a run of 20-round Lee Enfield box magazines produced.
The Lee Enfield SMLE remained the primary British service rifle, until being replaced by the L1A1 SLR (Self Loading Rifle) in 1957, which is the inch-pattern version of the FN FAL rifle.