thanks everyone who like my idea, I dont know why it never made it into halo 2 in the first place.
well it seem like, in that halo 2 video, the one shot firing had the same damage but was very fast and would pull just a bit less damage over a long distance than bursting from a short distance, they could slower the fire rate and make it more like the dmr when scoping and change the bullet damage to fit to get a good balance. For the rate cap, it depends if they change or not the bullet damage. If its like in the video where the bullet damage isnt changed and you need to fire very quickly to do a good damage, i'd vote for the hold the trigger and it shoot automatically like the halo reach needle rifle. Im highly against having a gun with no firing rate cap or a really small cap to avoid people using rapid fire controllers or something like that.
In my opinion, the burst damage should be exactly like Halo 2-3, and the scoping single shots should do a bit more damage with a decent firing rate cap (like the DMR, but with no bloom)
only thing is that it would be unrealistic ? maybe the gun would have two different bullets magazine that you'd need to keep an eye on your remaining ammo?
Another idea would be to have a br/dmr that can be switched manually for burst or single shots, thats it.