If you’ve seen the trailers for Ben Wheatley’s Free Fire, you’re probably expecting the whole thing to be one giant gun fight; a brutal and funny battle royal where an ensemble of criminals pick each other apart, one bullet at at time. Guess what! You’re right. If you’ve experienced the marketing for this film you going to get exactly what you expect, for better or worse. Mostly for the better!

The initial premise is simple: a couple of IRA members , Chris and Frank (Cillian Murphy and Michael Smiley respectively), are looking to buy a buttload of assault rifles from a sleazy South African gun dealer named Vernon (Sharlto Copley, being as Sharlto Copley as possible). The setting is an abandoned factory in 1970s Boston. Why the 70s? Beyond the vague backdrop of The Troubles, it’s mostly an excuse for fun costume design and a justification for the lack of cellphones.

The deal doesn’t go smoothly, what with Vernon getting the IRA’s order wrong and everybody generally being jerks to each other, but all parties are still standing and unperforated by the time guns and money have been exchanged. This is partially thanks to intermediary Justine (Brie Larson), who is a level-headed island in the middle of a sea of idiotic machismo. But then, thanks to an outside beef between two pieces of hired muscle, everything falls apart. Very fast.

As far as the action itself, Wheatley handles it very well. Almost all of the film takes place in a single open space, sprinkled with things to hide behind, and there is rarely any confusion about where people are in relation to each other. That’s something I need from action cinema, and Wheatley maintains it as characters crawl, stumble and limp about, searching for cover and ways to make other people dead.

A recurring (and wrong) criticism of Mad Max: Fury Road is that it’s nothing more than one long action scene. The same criticism can be made of Free Fire, but it doesn’t have the benefit of Fury Road’s loftier aims and thematic complexity. It really is nothing but an action scene, as well crafted and funny as it may be. The continual exchange of trash talk and flesh wounds is mostly entertaining but eventually becomes numbing. The running time may be short by modern standards, but I still think it could have been trimmed down. It’s a thin premise, stretched even thinner.

Luckily, the dynamics of the battle shift with enough regularity to keep you from tuning out, and the good stuff is very good. Late in the film, when several characters manage to split off from the main group and start Die Hard-ing their way through empty offices, the cross-cutting brings some much needed dynamism and urgency to the proceedings. It’s very exciting for an action climax where nobody can walk upright.

Vernon’s associate Ord (Armie Hammer) is another highlight. Ord is an immensely entertaining mixture of competency, dickishness and unexpected reasonability. He’s what saves the “bad guy” (whatever that means in this context) gun dealer side from being uniformly malicious and moronic. A foul mouthed and charismatic jokester figure, more than anything he’s annoyed to be caught up in all this nonsense.

Free Fire is what it says on the box: a chaotic and jokey slice of death-dealing. It’s funny and bloody and has some great, low-key character work going on. The action is solid as hell. When I say that the film doesn’t go in many unexpected directions, other than some rote twists, that’s not really a big deal. It has a tight little premise and doesn’t need much adornment. If anything, it could have been tighter.