This is a reference to the British cop comedy/deconstruction *and* reconstruction of cop film tropes Hot Fuzz, more specifically when Angel gears up (and yes, that includes the dual shotguns over the back) and the reconstruction starts up.
...Also, *GOOD FUCKING GOD THAT POOR GUN*
it's like a Martini Henry had a deformed child with a FAL (or a L1A1 to be more regionally accurate I suppose)