The JP36 is a well-rounded primary with good damage and excellent total ammo. Its main weakness is the relatively small pool of attachments available for it. Its high total ammo allows it to fill a supportive role and makes it an excellent choice for keeping enemies suppressed. With stability-increasing attachments such as Sniper Stock and Polizei Special, it has very low recoil and as such can be used even at far ranges, making it even more effective as a support gun.
The JP36 can also be a useful back-up weapon in stealth loadouts, with its modifications that provide high concealment (specifically the Compact Foregrip and the Solid Stock). It can easily make up for the player's possibly weak secondary in Plan B (assault) and keep visibility low during the stealth portion. However, its somewhat high rate of fire will be more difficult to control.
The JP36 is based on the G36K but fitted with the compact flash hider and picatinny carry handle of the G36C. With the Compact Foregrip attached it becomes a legitimate G36C.
When adding the Compact Foregrip to the JP36, the game may warn the player that the Long Barrel modification will be removed, despite the JP36 not having any Barrel modifications. This likely hints at the existence of a Long Barrel before it was removed from the retail game. A G36K fitted with the Long Barrel is essentially the baseline G36 rifle.
With a fitted Solid Stock it becomes a G36KV.
JP36 also happens to be the SKU number for the discontinued Echo1 airsoft X36. This isn't actually unusual, consider most of the guns in PAYDAY 2 are based on Airsoft products.
Prior to update #65, looking at the translucent magazine of the JP36 showed no rounds inside of it, the player literally loaded an empty magazine into the weapon every time a reload was started. From the side, the magazine also seemed to have the bullets being inside the magazine in reverse.
Contrary to the rest of PAYDAY 2's weaponry, the player characters all exhibits surprisingly poor trigger discipline when performing a melee attack with the JP36, as their trigger fingers are still in place during the entire process. Were the same melee technique to be performed in real life, the weapon would discharge by accident every time a hit is attempted, not to mention the animation itself is very awkward and seemingly weak and would not realistically cause any significant damage. That is, if its plastic magazine remains unbroken after the strike.
The JP36 is shown on the cover art held by Wolf and attached with a See More Sight, although the See More Sight had not yet been added to the game at the time. The same weapon (a Compact Foregrip is sometimes present) is also seen held by him in many other instances of game art such as the Bomb Heists splash image and various community event updates.
The awkward-looking sight featured on the JP36 is actually the weapon's long-range aperture. The real-life G36/JP36 iron sight group has two separate apertures intended for close-range and long-range aiming, with the close-range sight ring being broader and not as obstructive. The close-range sight is presumably flipped down in-game.
The JP36's ironsights are nearly identical to that of the Lion's Roar.
Although the JP36 cannot use Grip modifications, the Gun Modification section in The Guide of Bain shows the Pro Grip as a mod for it.
The Sniper Stock mod is similar to the stock of the SL8, a marketed "sporting"/civilian version of the G36, though unusual in that it has the G36's fire selector block. The SL8 is only capable of semi-automatic fire, and even when modded to full-automatic it would seem unlikely to include a selective fire function as seen and used in-game.