How rare is Long arm?

[BigBallinChester]

Because I beat the Spiral at least 6 times and never got it once. All I get is ♥♥♥♥♥♥♥♥ armor and that useless heavy machine gun and a garbage seventh seraph officer revolver.

[@xaker89]

random drop.

[BluefactorXL]

I got it 5-6 times in 9 runs, but no sidearm yet, it's just bad luck.

[and]

Farm the first encounter, it has a pretty decent drop rate. I've farmed the first encounter over 50 times for the helmet but all my drops were arms or the scout rifle.

[Salted Rogue]

I have everything except hat, grenade launcher and exotic weapon. Def random, gotta pray to RNjesus to get one to drop