The "feature" you describe is more accurately called a "3 round limiter". The 3 round still leave the rifle at the same speed they would on 'full auto', which means that if the soldier started with a COM point of aim, his third shot would impact at the top of the head or over it.
The "3 round" feature was touted as "increasing accuracy" during sales talks, but the reality fell far from the promise.
Heckler and Koch weapons have a real "burst" feature available on some of their lowers. When "3 round burst" is selected, the rate of fire jumps up to 2000 rounds per minute, providing one *BANG* and one recoil with every 3 round burst fired.