I have been maining as Jack when it comes to trapper these past 3 weeks and here are my two cents:
Revolvers - Don’t let them fool you, Jack’s primaries are a VERY good damage dealer. Probably on par with Abe’s shotgun because what they may lack in power, they make up for in accuracy. It’s easy to get headshots on the monster thanks to the reticle. They also reload quickly.
Scanner and Satellite - One complements the other here. Jack lacks the means to exactly pinpoint the location of a monster if it is far away. So what you want to do is the following:
Do NOT fire up the Scanner as soon as the team touches the ground. You will still be way far from the monster and you probably won’t be able to see it through the walls. Follow the tracks, the corpses and the broken trees and also keep your ears peeled for noises that monsters tend to make when they use a special move or jump away. Wait to get in a place where your eyes can adjust (yes, that’s a thing) to the darkness of your current position and then use the scanner to 100% make out the monster’s sihlouette through the walls. This also confuses the monster since most people do the mistake of using the Scanner right away.
The Satellite is good for effectively trapping the monster without using the dome. This usually happens because I have found it to be very effective in map cones. Unless the monster decides to break THROUGH your lines, it is gonna end up in the edges of the map. Keep your distance and use it to ping the monster to corner it and wait for your teammates to come in to dome it. Never underestimate the range of the Satellite but also, NEVER use it if the monster is still running in what you believe to be a straight line. As soon as you think the monster has starting drawing turns on the map, the Satellite will tell you where it is. If your Satellite misses, then you can be sure your Scanner will lead you straight to it. Just don’t fire it immediately after your Satellite misses. Give it a bit of time to play with the monster’s patience and once you have covered enough ground based on how far is the most recent footprint, Scan for it.
Keep an eye on the map and have your teammates follow you because with Jack, it happens quite often for you to find the monster and have nobody close to you in order to dome it safely. You are the only one who can interpret the tracks shown by the Satellite and the only one who can see through walls with the Scanner. Abe’s tracking dart, Griffin’s sensors and Gobi, they all show the monster’s position to EVERYONE. Jack doesn’t have that so wait up for your teammates.
Repulsors - Jack needs BOTH capacity perks in order to be an annoyance to the monster (at least in the beginning) but the repulsors don’t need to be at 100% capacity in order to work. With both cap perks on, every jump you block decreases your capacity by 30% and to be a bit specific, the Goliath’s charges are automatically negated. The repulsors can work via lots of angles but all of them include being IN FRONT of the monster. It doesn’t matter where YOU position yourself. If stopping power is what you want, it matters where the monster’s headed to. THAT is what determines your positioning choices.
They also have a ridiculous range. Try being as far as possible while in front of the quarry. Distance has saved my ass tons of times.
Finally, keep an eye for the monster’s animation. You have to learn to predict what’s about to throw at you in order to effectively block it. The best guesses usually lead to monsters getting landed by force, mid-jump