Even after your tactics and aim improve, this will still happen. Shotties are really inconsistent (lag maybe?).

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My two cents...get your hands on a better shotgun i.e. party crasher +1, silence of a'arn (my fav), next big thing, invective or pray to RNG for a universal remote... mistakes as per the video...there was a lighting grenade right next to you and there were two opponents...as others have said you need to get more tactical and find a way to sneak up on your opponents. Also learn to use crouch...especially coming round corners or hiding spots...this comes from learning the best parts of the map that allow for these things to happen...yould be surprised how many times people have run right past me when hiding in the right spot...if you've got a upgraded hunter use the invisibility crouch as this gives you that extra stealth to sneak up on people...practise with that and you should start getting some more kills and have more fun with it...

In the video, your movement and pathing is very "railed", like you were following a pre designated sidewalk. You even turned that corner like you were in a military formation. Don't be easy. Make your foes use more energy to pursue you and break their cover instead of the other way around. Make a trap, after you bait them by seeming an easy kill, jump above the corner/door they are following you through. Don't believe the current paradigm that shotguns are for rushing. Successful shot gunning requires a lot more tactics then pressing sprint. Above all else, radar is your enemy. In order to have the element of surprise, you'll need to hold back, observe the combat quickly and make sure you attack when the prey is distracted. Take the least used path (in the case of the video, the lower ground to the right outside, then jumping up beside them as they are distracted with your team.) this way, they won't be watching the radar and you can get in and out, with some finesse and luck. Also, don't use the current meta. It makes weak minded shotgunning. Use Invective as a starter. If you can get better using it, you can move on to longer range shotguns. However, the higher rate of fire ones are best suited for room clearing. But that's a choice on playstyle. Edit: I forgot to add, my Hunter has my setup of you want to look it over. Keen scout and graviton forfeit will help tremendously. Don't stay grounded, but also don't leave yourself exposed, try to cut your jumps to just what's needed, as you can't skate.

use vertical space, try leading with a grenade and always follow up with a melee

In that video you were being too predictable. Also there were two opponents vs you. Unless you approach under the right circumstances it's a battle you'll always lose. Best tips for shotguns, make your movements harder to predict such as jump shots, slide shots or going to places where hardscopers pitch tent e.g. other side of Pantheon. Don't engage when you're low health unless you know you're going to pinch the kill.

I'm not the best with them either, but I'm badass with fusions and I have some tips for them if your interested.

You are using a shitty shotgun. Also your movement is too predictable

If anything... it's probably that you're outside of handshaking distance.

Please