I used Ether Doctor for my auto rifle and multi kills. you can take enemies down fast with head shots. when you get Breakneck you will have fun using it in gambit. I like it for strikes and most pve activities when you get kills the rate of fire increases making it really easy to take enemies out fast. i think it may have outlaw or at least some reloading perk, when you get precision kills the reload is increased. I really like it and definitely is worth the grind. I added back up mag to mine and it holds 45 shots.

Even if you don't have all the new AR's, Uriel's Gift, Positive Outlook and Origin Story all work fine. Plenty of range with all of these and you can pick Kill Clip, Rampage, etc. depending on which of these you use. I did the Breakneck quest on my first guy with these. If you are working on AR kills use say Origin Story with rampage (comes that way from Collections). Kill the easiest target first then work with Rampage. If you use Origin story you can keep your special slot open to deal with shielded enemies. Keep in mind too that 40 matches is way more than you need to get the AR kills for Breakneck. You can easily have all the kill stuff done by match 24 or sooner, so you don't need to run dual AR's to get it done. You can do it

[quote]Damage fall off for auto rifles is appalling. They reach barely farther than shotguns with a mere fraction of the damage per second. And it gets pretty tedious when my teammates decide to hang out away from the freshly spawning cluster of enemies and I have to chip away at this shielded enemy since my special weapon doesn't match elements.[/quote] That's because if they did, we'd have the Uriels Gift meta all over again. Noooo thaaaanks.

I used Age-old Bond for my auto rifle kills and multikills for Breakneck. Each bullet does the same damage as Bygones bullets. AoB has really good range for being an auto rifle. And it's an energy weapon, so it does pretty well against enemies with shields, too. Especially when you're facing Vex.

If you’re trying for those auto rifle kills, I suggest using Cerberus+1 (if you have it). Very good for multi kills and auto kills, but have to be closer than normal.