StormKnight,
It's possible that this game is a little more freeform than what you're used to playing. It won't give you hard, rulebook-based answers to "how do I handle this particular situation"? Part of it is the group cohering together around the rules (e.g. over time you establish, together, what exactly it means to use "Act Under Pressure"), and part of it is you using your own MC (GM) instincts to create the game you want to play.
In every case, establishing in more detail what is happening will help you.
For instance, in the scene with the poachers, we have a character using an item/ability to disarm an approaching poacher (who is clearly on the defensive enough to have drawn a rifle, but not aware of the actual threat the PC represents just yet). Well, how alert is the poacher? What are the others doing? Where are people standing, who's got weapons drawn, who's ready for action?
It's a perfect opportunity for "Read a Bad Situation", because rolling that move tends to nail down a lot of these questions for you. ("Read a Bad Situation" is built for these kinds of circumstances, exactly!)
However, if the player doesn't want to do that, then what?
You have a few options, but here are the most obvious ones:
* Let the PC do their thing, then respond with an MC move.
"You pull the rifle from his hands, catching him totally off-guard. He's just standing there, slack-jawed." [narration, description] "The other poachers yell and draw and level their guns, rushing forward to surround you. What do you do?" [MC move: put someone in a spot]
* Tell the PC that they're in a tense situation and they need to "Act Under Pressure" if they want to do that.
How do you decide which? A part of it is instinct, experience, and going with the group's current "vibe" or attitude.
Another part, though, is figuring out if there is, indeed "pressure" at play. What are we afraid of here? You always want to nail that down before rolling "Act Under Pressure", so that it doesn't feel weird when the dice hit the table (you know that feeling, when there's a miss and you're stuck wondering what to say? you don't want that).
Maybe it's been really clearly established that the poacher is paranoid and trigger-happy, and that the PC's item/ability takes a moment to work. Under those circumstances, it's obvious to everyone that what the PC is doing is *dangerous* - this guy has the aggression, the intent, and the time to pull the trigger.
On a 10+, whew! Maybe the gun goes off, but the danger does not come to pass.
On a 7-9, offer a hard bargain: maybe the PC has grabbed the poacher's rifle, but he ain't letting go of it, and now the other poachers are drawing weapons, too. If you don't let go, you might get shot or worse!
On a miss, you make a move - but the most obvious one is usually the right one: she gets shot before she can do it.
If none of that is clear before you roll, spend some time talking about the situation and establishing those details. If you haven't and everyone suddenly wants to roll, it might be as simple as, "Hey, how does that item work? Is it fast, is it slow? Does it make sense? How well can you control it?", or maybe it's just, "Ok, sure! But you can see this guy's really nervous, and the knuckles are going white around the rifle - he's THAT close to just pulling the trigger. Still want to do that?"
On the other hand, maybe this poacher is nervous and he doesn't have the guts to pull the trigger. In that case, snatching the gun from him is not the challenge. Is something else? Maybe the other poachers are more determined than he is, and snatching the rifle will spur them into action. Then THAT is the pressure that she's under.
On a 10+, she pulls it off, and she's got the initiative. What does she do next?
On a 7-9, she pulls it off, but something bad happens, too. She grabs the gun, perhaps, but the poachers open fire and hit the Hunters' car! Now we're in a fight.
On a miss, she pulls it off (remember, we decided it wasn't the challenge here), but you make a hard move on behalf of the poachers. Maybe she gets shot, if that's the most obvious thing, for example.
The exact outcomes are up to you; that's how you MC a game like this. It's possible that it's just too loose/freeform for you! If so, that's very understandable; a more strict by-the-book kind of game (D&D4E?) might suit you better.
You could also make it a little stricter for yourself by stating the possible outcome of a miss before the roll, though ("You've got to Act Under Pressure if you want to do that. This guy is ready to shoot; miss and he'll be faster than you!")
Again:
* The game works best when you establish as many of the fictional details as you need, first.
* Reading a Bad Situation could help answer a lot of these questions for you before you even do anything. This is exactly what it's for!
* If not, describe what's happening in more detail, nail down what the deal is and what threats there are. In the process of hashing it out, you'll get a sense (as a group) of what the best move or choice here might be. ("Ok, so he's not dangerous, but there's two guys in the back who look like they're ready to fight/run/do something stupid? Cool. You'll have no trouble getting his rifle, but what are you [looks at another player] going to do about the two at the back? You're closest to them.")