I don’t know of any modifications made to the M1919A4 or A6 to use link belts. If so, it was not something that changed the designation of the guns, as far as I know, and the guns remained able to use cloth belts as well as link belts. Most of our training was done with cloth belts, while TO&E Infantry Units mostly had link belts, I believe, when I was involved with these guns in the late 1950s. I seem to recall some training about the maximum number of rounds that should ever be linked together, so that the belts were not too heavy to be dragged thru the feed cycle by the feed pawl, but I don’t recall if that was while I was in the Regular Army, or later in the Active Reserve. Generally, the cloth belts were only loaded with 250 rounds, although as a souvenir, I have a GI can for 250 rounds with the extra clips for mounting the ammo can to a stationery mount, like a vehicle mount, or the early 1917-type tripod (I think - been a long time!!!). However, the belt in it, which is olive drab, not white, has no metal feed tab and instead an arrangement whereby to of the cloth belts (or more, except I think they would be too heavy to feed properly) could be joinged together by inserting a cartridge there. I only have one of the belts.