Filmmakers can find inspiration in lots of places. Classical literature, plays, other films. Director Ben Wheatley, however, found the inspiration for Free Fire in two unlikely places: The comptuer game Counter-Strike and an FBI field report.

Those obviously aren't the only two influences on his movie about two gangs having one very long, very bloody shootout over a deal gone south, but they're certainly integral to the DNA of the latest movie from the director of Kill List. As Wheatley told us, he based the location of the movie - which is largely set all in one space - on a Counter-Strike map that he's been playing for well over a decade. Combine that single set location with an old FBI report Wheatley read about how actual shootouts go down, and you're on your way to understanding the tone of this raucous crime thriller.

We spoke to Wheatley and one of his stars, Sharlto Copley, about Free Fire after it played SXSW back in March. And just for a little context - particularly since the interview was interrupted, as you'll see - our chat took place at a fun event held at a place called Stunt Ranch, that has a paintball field, a high fall, and a big area for trapeze performances.

Movies.com: What itch was this project scratching for you?

Ben Wheatley: I wanted to make an action movie. I wanted to make a crime film and play in that sandbox. Some of my favorite movies are action films. That's what started it off, really. I'd touched with bits of actions in my other films, sequences that would be just a few minutes. So I wondered how I could stretch it out. How much can you get away with? The structural challenge of that. Can you stretch this to the whole running time of the movie? Is there enough story for that?

Sharlto Copley: I wouldn't say there wasn't a specific itch I hadn't scratched yet. It was after talking to Ben. [Someone from the Stunt Ranch interrupts to inform us the trapeze is now open]

Wheatley: I think we should do the rest of this interview from the trapeze. You can only get an answer if you catch the other person.

Copley: I've actually done trapeze at a place called Zip Zap Circus in Cape Town. They catch you and let go and someone else catches you. It was pretty nuts.

Wheatley: How'd you feel after?

Copley: It was pretty cool, man. Pretty exhilarating. I wouldn't do it now. [laughs] I was much younger then.

It was a chance to do a South African character, a proper one, and Ben was really open to that. I also wanted to do a certain level of improv, and as a director Ben was really open to that. It's a collaboration with Ben and Amy [Jump, writer] to create the character.

Movies.com: Where did the initial germ for the idea of the movie come from?

Wheatley: I was reading about a shootout in Miami where the FBI had cornered these guys who had just robbed a bank and had armor and all this stuff. It was a massive shoot out. I think it went on for something like 40 minutes. Afterwards the FBI guys all had to write a blow-by-blow report of what happened. And I read this report and it was really kind of alarming. It was random and messy and not like anything I'd ever seen from cinema. Now it's no great epiphany that Hollywood isn't realistic, but it was both terrifying and interesting. That was like fifteen years ago that I'd read that, and it had just been going round and round in my head. This close quarters stuff was something I hadn't really seen before. A lot of shoot outs are just shots of people firing and then shots of people falling down, and that's what I think people have this perception of it being a bit dull. The tactical side of it is much more interesting.

As much as cinema influenced it, video games influenced it for me as well. I've been playing Counter-Strike since version 1.

Movies.com: Do you still play?

Wheatley: All the time! But I'm terrible. I play GO and I'm just no good. I just enjoy it. Assault is very similar to this in many ways. There's the office that overlooks the thing with the staircase leading up to it. You'll see it now.

Movies.com: How much of the mechanics of the shootout did you have planned in the script and how much of it changed based on location?

Wheatley: It's always a negotiation. There's a lot of planning that goes into, but I always want to give space to an actor to try stuff because I want to see what they've got. But when I saw the space it changed the script. There were elements that were, from a directorial side, improvised when I saw opportunities. There's a bit with Noah Taylor and a drum that he kind of wheels down, and that was improvised when I saw this massive cable drum on set. But what was your experience, Sharlto?

Copley: Ben is very actor friendly and creates this experience where you have the space to play around and he lets you make moments. That's actually quite rare for a director. Before I worked with him, my agency said 'Everyone who has ever worked with him raves about him, so even if you don't like the script, just talk to this guy because he's incredible.' And that was really true. It was incredible to get to make a movie with him. What he said about giving space was really true. Some actors like it more than others. I really enjoy it. It was a great chemistry.

Movies.com: When you two first met, is it more of you as a director trying to get him on board or is it more you as an actor trying to get yourself on board?

Wheatley: It's just seeing if you like each other. It's basically like speed dating for me. If you have any kind of a connection you go from there. It's about trust. Do I trust this guy? Does the actor trust the director? If they do, we're going to get on alright. He's got a high bullshit detector and I do too, so I knew it was going to be alright.

Copley: You talk a bit about how you see the character, how you see the movie. That first meeting is when I try to see if his idea is close to my idea.

Movies.com: There's a pretty significant amount of bodily harm in this. Where do you set the limit for how many bullets a person can take?

Wheatley: From the FBI reports, as far as pain goes, you can take quite a lot as long as you're not hit in the head or the body mass.

Copley: It depends on the calibre, too.

Wheatley: Yeah. If you get shot by a Barrett rifle, there's no surviving that even if it hits you in the toe. But for some of the smaller pistols, the .38 and stuff – not that I would want to test this out – but they're designed for shooting in rooms, not in bigger spaces. This is a problem that people have, because television and movies have educated people in a very particular way, but [bullets] work differently.

The thing I read, and this was crazy, that the cops would drive up in their cars and would duck behind their cars thinking they were safe. But when a bullet hits the ground, it doesn't bounce like a tennis ball, it kind of aquaplanes and then goes straight along the ground. So if you're hiding behind a car, you can get hit by that. You wouldn't think about it. And it does the same thing on a concrete wall. If you hit it at 90 degrees, it doesn't bounce, it goes [like flat] and people get killed that way. They had to educate the police about this, because they'd learned that if you hide behind a car, you can still get killed.

Free Fire is in theaters now.