Page 81 of Savage Worlds Deluxe Explorer's Edition says:
Double Taps & Three Round Bursts A character with a semi-automatic weapon (such as a Colt .45, an M1 Carbine, or even an M16 [my emphasis]) can fire two shots in one action by "double-tapping". [description of double tap rule follows]
Many modern automatic weapons, such as the M16A2, have a selector switch that allows the user to go from single shot, to burst fire, to fully-automatic as a free action. Burst fire, or a Three Round burst, gives the user [description of 3RB bonuses follows].
Pages 54 and 55 describe the various notes that can be attached to weapon stat-lines. They list:
3RB: The weapon has a three-round burst selector (see page 81).
Auto: This full-auto weapon may fire in automatic (single shot) mode.
Double Tap: The weapon can rapidly fire two rounds. [rules follow, identical to the rule presented on page 81]
Semi-Auto: The weapon fires on semi-auto and can take advantage of the double-tap rules (page 81).
In the gear listings on page 61 and 62, the Colt .45 and M1 Carbine have the "Semi-Auto" note. But the M-16 has the "Auto" and "3RB" notes. It is not listed as having "Semi-Auto". There is no distinction in the gear listing between an older M16 and the M16A2.
None of the weapons in the gear list are actually tagged with a "Double Tap" note; I assume this is an editing glitch, since that rule has been rolled up into the "Semi-Auto" note.
Question 1: Should the listing of the M16 in the rule on page 84 be interpreted as implying that any "Auto" weapon also counts as "Semi-Auto", and can make use of Double-Tap? (e.g. Tommy guns, MP40s, AK-47s, etc)
Question 2: Can only weapons which are explicitly noted with "3RB" make use of the Three Round Burst rule? Can users of other automatic weapons (without a 3RB selector position) make use of the Three Round Burst rule via fire discipline?