There are a couple of YouTube videos out there of full auto M-16 “meltdowns”, firing them as quickly as possible until the weapon fails. It usually happens at well over 1,000 rounds. That’s using both drum and standard 30 round magazines.
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“...firing them as quickly as possible until the weapon fails. It usually happens at well over 1,000 rounds. That’s using both drum and standard 30 round magazines.”
The indefinite sustained-fire rates permitted under armed forces regulations are much, much lower than most people imagine. Probably set that way to maximize useful service life and reduce parts breakage.
M14 and M16 rifles: 20-30 rds/min
Machine guns (open bolt, air cooled): 60 rds/min.
In action, all bets are off.
There are tales from the Falkand Islands War of 1982, about the British firing their L7 guns (license-built FN MAG) until the barrels became white hot, then swapping them out, laying the hot barrel on the frosty ground where it would sizzle.
Old hands from US Army and USMC have told me that if one fired five magazines (100 rds) as quick as one could through the M1918 BAR, the barrel was toast. Recommended burst length even in tactical situations was 3-5 rds.