Justin Bieber Shooting Guns Shirtless

Justin Bieber's not standing on business, he's standing on bullets ... because he went shooting out in the wilderness, and took his shirt off to fire off a bunch of ammunition.

Check out these photos the singer just posted on his social media account ... Justin's in the great wide open squeezing off rounds from rifles, shotguns and sidearms.

Justin ditched his shirt for the shooting spree ... and he brought some extra guns along ... because, as you can see, the dude is kinda jacked underneath all those tattoos.

The Biebs brought plenty of bullets with him ... just look at those huge ammo cans ... and it appears he was doing a little skeet shooting, at least when he had the shotgun in his hands.

Justin's been having himself one hell of a summer ... with lots of outdoor adventures with his family and friends ... and plenty of shirtless snaps.