Wasn’t there also a planned SAW version of the M14 with a heavy barrel and a pistol-grip that was decided against adopting because “muh infantry M14 can fill all those roles anyways!”?
yes, the M15 SAW, which was actually adopted but never was pursued in favor of the Colt model 606 in both A and B variations as well as a few experiments with the then new M16 that the Army and Air Force were trying to standardize on. there's a lot of stories circulating around the time period about the development of the M16 and the immediately preceding M14 that was replaced so swiftly.
What was so bad about it exactly (assuming this is a serious answer and not just shitposting)? I always thought that ballistically it was between 7.62 NATO and 7.62x39, and both of those are perfectly adequate service cartridges.
the .280 was functionally uncontrollable in automatic rifles for common infantrymen owing to British doctrine at the time of self loading rifles for accurate fire at all times with only line gunners offering automatic fire. that and generally poor performance for the size of the round which did not significantly increase the "firepower" of a fireteam either through volume or through accuracy. if anything, it was a step backwards from chemical and mechanical developments since the end of WW2. the three or more years of development time with the T61 and T62 ammunition essentially created a "compact" .30-06 Springfield cartridge, which offered better overall performance for the same cost in both manufacturing, logistics, and doctrine while also being more compatible with existing .30 bores in machineguns in service. it didn't help that the US Army was significantly misguided in a single cartridge for all arms which just wasn't feasible at time just like how "walking fire" wasn't a useful doctrine in actual practice. the .280 did work for burst firing or single shot rifles and carbines though and was sufficiently useful at 500 meter engagements, which the US Army refused to acknowledge until decades later - instead insisting that 800+ engagements were viable and desirable... until you know Vietnam. not like the British had experience with jungle warfare and full power cartridges for 20 years in Malaysia fighting communists or something - that apparently didn't count.
if you want a modern equivalent, 7mm-08 Remington is still produced and is a popular hunting cartridge, i've used it in a Steyr Scout and it's a very nice, flat shooting and mild cartridge that's still significantly powerful for medium game like fully grown red deer or reindeer. 6.5 Creedmoor might be an equivalent in an automatic rifle.
It's a good thing they kept the magazine, stock and trigger/safety setup because otherwise that sounds like 'all you need to do is replace the entire fucking gun' L85A2 style.
i've built one for a customer, it's entirely the same as a normal M14 (or M1A) other than a half dozen assemblies, 3 of which are simple adaptions of already existing items (gas system, muzzle device, recoil buffer). the rest were very straight forward modifications to the stock, bolt, and operating rod. in terms of effort it's similar to assembling a M16 upper from parts - doable with the right tools and experience in an hour or two at most.
in the 1960's, the M60 and M14 were in active production and many spare M14 parts could also be sourced from WW2 surplus, combined with straight-forward mechanical changes it would have also been economical as well. too bad it wasn't really thought of until decades later.
