Johnson .30-06 Military
This rifle was developed to be a semi-auto/full auto, to fire from a closed breach in single rounds and open breach when on full auto.
The reasoning for its design was that in single fire, the breach should be closed to minimize jump. But when in full auto, the breach stayed open for cooling.
At that time, late 30's when it was designed, I think by Johnson who was a government designer in Springfield.
I can recall them being advertised in the National Rifleman for $89.99. The good old days, eh?
From the experiences in WWI, the Bren was desinged as a light MG but in both single and bursts, it fired from an open breach. I am not sure about the US BAR.
In my own experience with a Bren, set on bursts, it was capable of very accurate single rounds, each aimed with trigger control. I got s**t from NCO's who #####ed when I aimed each shot and they wanted 2-3-2-3 bursts. I said check the f******g target, I got both mags off in the alloted time. e best.
I am unsure if any other WWII LMG satified this quest. Perhaps the German LMG M34?
SOF