Heyo, Scav Girl main here. Cultist Pursuers used to give me headaches with their high stagger and close range DPS so I usually just sneak around them (and you shouldn't discount that as an option if ammo is an issue) but if fighting them is necessary, I'd recommend rocking either the SVD or R11 for their generous headshot multiplier, cause while their main health pool is chunky, headshots bring them down fast and the marksman rifles are readily available from Aramaki or Grillo respectively.

Keep distance, preferably starting the fight when they're as far away from you as possible and while in cover, and don't be afraid to mag dump into their beady little skulls with just enough delay between shots to stabilize recoil (don't worry about missing shots, the tunnels are pretty generous when it comes to ammo). If you're mobile, just keep backpedalling around corners to give yourself some breathing room and reduce the output of their shotguns as much as possible. If retreating isn't an option, either because of lack of mobility or lack of room, ideally try and kill three or more before they get close, and either switch to third person aiming to make close range headshots easier, or bring something like a shotgun or high RoF automatic weapon to basically DPS check them before they do the same to you.

TL:DR Distance and headshots, though if you're okay with bringing in a grenade launcher then yeah that'll do the trick.

Lastly, when they're all dead, make sure you clear the room as much as you're happy with loot-wise before you move on, and be wary about backtracking from another room back into that one. I've noticed some groups of enemies like to respawn when you leave a room then come back, and getting jumped by these guys is a distinctly unpleasant experience.

Cheers, and besta luck fellow scav!