This is a double-boxing boosting method only.
If you can’t double-box, I’d recommend the three person Medic method.
You have three primary weapons for each class, so a total of 12 guns. To gold star you’ll need 100 kills with that specific weapon, so a total of 1200 kills. Keep in mind it takes roughly 40 minutes to gold star one weapon so you’re looking at an estimated total 8 hour grind.Now onto the boosting method:
You’ll be using the game mode Squad Rush on the map Operation Hastings with Hardcore enabled. Hardcore just makes the enemy easier to kill, therefore using up less bullets resulting in more kills before you have to replenish your ammo reserve (i.e. committing suicide). You’ll also want to join the match first, as the first person in is the attacker. Once in, join with your dummy.
As the attacker, destroy M-COM A. Once destroyed, move to M-COM B. This is where you’ll be doing the killing. Looking at the map, furthest southeast is where the defender (your dummy) will spawn. Because you can’t go past a certain point as the attacker, you’ll want to get as close to the map boundary as possible. There’s a stone wall adjacent to the boundary.
In other words, as the attacker, run past M-COM B to the stone wall. Stand on the post directly in the corner of the L-shape, from here you’ll be able to see the defenders three distinct spawn locations (at this point you should be looking at a river). There should be some sort of palm tree to your left and a tree to your right. You’ll want to stand as far forwards on this post without going into the “Turn back!” territory.
Your dummy will either spawn to your left (behind the palm tree), right (in opening between tree and other palm tree), or directly in front of you. Two spawning points on the right, you can just shoot him without moving, if he spawns furthest right, you’ll have to move him slightly left. Each time he spawns on the left, you’ll have to move him right towards the center. He’ll spawn twice in the center during one rotation. If at some point you can’t find your dummy, try shooting and if he’s left you’ll see his bullets flying, if not, he’s most likely furthest right.
When you run out of ammo simply press Start and use the “suicide” option. Always go for headshots and try to preserve ammo. Also would recommend using the larger mag perk. Hope this is helpful to you fellow double-boxers. Good luck and happy hunting!