Suppressor and Fuel rod gun

Near the end of one of the oddball game clips on the map exile, one of the players is using a forerunner weapon that is very similar to what the suppressor looks like in screenshots. When I looked at the diagram of the weapon and the amount of rounds left in the clip, up in the right corner, the it had a different set-up than the light rifle, which probably proves it to be the suppressor. What really got me interested in it was that when he shot the weapon, the “bullet” count went down by 3 rounds every time he fired. I was wondering if anyone knows if the suppressor is suppose to be a fully automatic weapon like the assault rifle or a 3-round burst rifle like the battle rifle?

Also, if anyone has seen the new ViDoc that came out at PAX that was titled “A Hero Awakens”, around 2:58 to 3:00, you can see on the screen in the back a player that looks to be carrying a fuel rod gun. It not only looks aesthetically like the fuel rod, but it even has 5 rounds per clip.