When the US replaced the M1 Garand, the plan was to adopt both a select-fire infantry rifle and a heavy-barreled support weapon on the same platform. During development, both the T44 (later M14) and T48 (FAL) rifles had heavy-barreled versions. In the case of the M14, the final iteration of the heavy-barreled weapon was the T44E5, which was formally adopted as the M15. Before it could be actually put into production, though, it was cancelled as unnecessary.
In testing, first the Marines Corps and then the Infantry Board found that fitting a standard M14 with a detachable bipod gave the same performance as the M15 – and so why bother with an extra version of the gun? Of course, the equal performance was really quite poor compared to proper light machine guns, and once the M14 got into service this shortcoming was noticed. this led to the M14A1 aka M14E2 project, to essentially recreate the M15 with a pistol grip stock and front grip.
Thanks to the Springfield Armory National Historic Site for giving me access to this truly unique specimen from their reference collection to film for you! Don’t miss the chance to visit the museum there if you have a day free in Springfield, Massachusetts:
https://www.nps.gov/spar/index.htm
From all that I have read about the M14, the problems with it seem to be about manufacturing quality control, rather than design flaws. If the manufacturing was better, might it have lasted in service longer and delayed the adoption of the M16 (or something else of a more current design)?
So it they decided to cancel the M-15 because one could get the ‘same performance’ with an M-14 plus bipod. But no one noticed that performance was poor until it was too late? That beggars belief. Back of that version one suspects a tale far more convoluted.
[OFF-TOPIC so ignore if you wish]
ALTERING NEWS w.r.t. XM8
so far: it was Heckler & Koch product https://guns.fandom.com/wiki/Heckler_%26_Koch_XM8
now: it is Sig Sauer product https://www.armyrecognition.com/news/army-news/2026/us-army-designates-m7-carbine-variant-as-xm8-for-faster-handling-in-close-combat
Observe that XM8 is supposed to be more compact version of M7 AND does lack stock folding hinge.