Meet the “Bundle of Joy,” a .50 BMG rifle that folds up and fits in your backpack.
These images were posted to imgur by Redditor SerbuSpecial. The weapon shown here is a Serbu RN-50 with a Law Tactical side folding stock. The barrel is 18″ long with an overall length around 22″ after the weapon has been fully collapsed.
The entire thing fits easily into the primary compartment of a backpack, making it one of the very few .50 BMGs that’s “backpack portable.”