From Benedict Point, you're going to take a voyage to Gaptooth Breach. There, you'll find a crew of miners that purportedly have a gatling gun that they found somewhere in the wilderness. Then again, the veracity of Irish's claims can't be verified, considering your failed attempt to retrieve a machinegun in the previous mission. As you ride with Irish towards your destination, he and John will bicker back and forth. Did Irish deliberately lie to John earlier, or is he just too drunk or stupid (or perhaps both) to realize the error he made? Either way, he promises that all will be right this time around. When you reach the entrance to the mines at Gaptooth Breach, Irish will tell you precisely how to get the gun out of the mines and to the surface, where the weapon can be taken away and used in our eventual assault on Fort Mercer.
Getting into the mining compound isn't an easy feat, nonetheless getting into the mineshaft where the machinegun itself is located. As you walk towards the entrance to the compound, you will be almost instantly intercepted by two horse-bound miners. Wielding guns, these guys go out of their way to let you know that you're about to enter private property, and if you insist on coming any closer, they will have to deal with you. The game will prompt you to use your Dead Eye skill to take the two targets out quickly, but there really isn't a need. Wield your weapon-of-choice and quickly cap both of these foes. Once you've scoured their bodies for money and ammunition, you can then enter the compound itself. Once you do, keep a close eye on your HUD, as enemies will begin pouring out of the woodwork (represented, as always, by red dots on your HUD). A repeater will go a long way here, since you can deal with a majority of the enemies you encounter without having to get close enough to be in any real danger.
From the entrance to the mining compound, the shaft is located ahead and to your right. Even though some enemies will spawn from the left side of the compound, most of them (if not all of them) will go rightward to defend the shaft entrance. So this will be a pretty one-dimensional fight in regard to where you need to direct your hostilities. Whatever foes defending the shaft that you couldn't (or didn't) eliminate from afar you'll have to fight in close-quarters, but none of these guys are exceptionally challenging or well-armed. In fact, if you can group some foes together, you can take advantage of their close proximity to one another by using nearby explosive barrels to filet enemies en masse, so long as they are in the vicinity of the explosion. Either way, when the coast is clear, head into the mineshaft itself. Just remember to scour all of those bodies for money and ammunition before doing so.
Meandering your way through the mineshaft is child's play. Your route is completely linear, and it's virtually impossible to get turned around or otherwise lost. A yellow dot will shine like a beacon on your HUD. That's your destination, but there's only one way to get there, so don't worry too much about navigation. What you will want to use your HUD for instead is an early-warning sign. Enemies will appear as red dots, and since there are a lot of twists and turns in the mineshaft, you will be able to fully anticipate an enemy's location, and be prepared for the ensuing fight, before ever being fired upon. Going blind without using the HUD will make your life a lot more difficult, so use it to the fullest extent you can. When red dots appear on your HUD, be prepared to fight. This will be a regular occurrence as you head through the mineshaft.
The indiscriminate slaughter of the hard-working miners you encounter would likely fill you with more guilt had they been unarmed and lacked any sort of aggression. But that isn't the case here. These guys don't much like you, and you don't much like them either, so don't let guilt overwhelm you as you slaughter a solid two dozen of these guys as you move towards the yellow dot on your HUD. As you get closer and closer to your destination, more and more enemies will appear, until you reach the chamber you've been searching for. The last miner holdouts will make themselves seen here, so take them out, and then approach the cart ahead. And remember -- if you're having trouble in the shaft or chamber, there are more explosive barrels to take advantage of. Just remember that these detonations can harm you too, so be careful. And leave none undetonated, since enemies could easily flip the script and use them on you at will, should you leave any behind.
Once all of the enemies around you are dead, it's perfectly safe to approach the mine cart (which is what the yellow dot on your HUD has been representing since you've walked into the mineshaft itself). This mine cart must now be pushed to the elevator on the other side of the shaft, the one that is typically used to hoist precious minerals and scrap rock to the surface, for sale or disposal. This time around, it will be used to bring a machinegun to the surface instead. The game will give you some heads up (via prompts) that you can pull a gun while using the mine cart, and that if the cart builds up enough steam, it will allow you to ride on the back of it. Neither of these techniques are especially useful within the shaft itself (so long as you killed all of the enemies you encounters en route), but they will be later, so keep it in mind.
