Weapon Name- 25mm Pump-Action Grenade Launcher
Round Type- 25mmx40mm
Over-all length- 1041 mm (41 in), stock extended
Barrel length- 22 in (560mm)
Weight- 4.5 kg (9.9 lb)
Rate of Fire- 4 r/s (Semi-automatic)
Feed Mechanism- Underbarrel Tube
Round Capacity- 6 + 1
Effective Range- 500 meters point, 800 meters area, 300 meters Flachette Ammunition
Range- 1000 meters
Accuracy- 2.5 MOA
Accessories- Picanty Rail
Quick switch firing mechanism- Fire Selector
Scope/Sights- Picanty Rail
Muzzle Velocity- 200 m/s
Firing System- High Low Firing System
Miscellaneous/electronic information- Essentially a pump action or semi-automatic underbarrel tube fed 25mm grenade launcher that combines both the M203 and XM320 grenade firing system with the Spaz-12 body and loading style with an increased barrel size, and different but similar firing mechanism.
Basic Information
Essentially a pump action or semi-automatic underbarrel tube fed 25mm grenade launcher that combines both the M203 and XM320 grenade firing system with the Spaz-12 body and loading style with an increased barrel size, and different but similar firing mechanism. The weapon, which essentially goes from a .729 inch diameter barrel to roughly 1 inch diameter barrel, was relatively easy to manufacture using the existing Spaz-12 shotgun, which provided the most utility, and recoil buffer and firing system area to serve as a viable base weapon platform for, essentially, a "1 inch shotgun", or in other words a shotgun that could be the equivalent, in most respects, to a 4 gauge shotgun. Another advantage of the Spaz-12 was it's viable shotgun shell length, being capable of holding up to 8, 3 inch shotgun shells, which allows 6, 3.5 (3.55) inch 25mm grenades to fit comfortably in an underbarrel tube of roughly the same length. The weapon, externally, is essentially a Spas-12 shotgun blown out to handle a cartridge that is 25mm in diameter, rather than 18.5mm from usual 12 guage shotgun shells, and having a slightly enlarged breech to allow the 25mm round to fit comfortably in the chamber.
Internally, the weapon is pretty similar to the Spaz-12, except for the blown out firing system. The weapon is basically fitted with a High Low Firing System found in weapons like M79, M203, and M320. Given the relative similarity of the loading mechanisms of the M79, M203, and M320, to shotguns in general (The M79 is an open breech single shot method, the M203 and M320 are "Pump-Action") it is relatively easy to configure a pump action under-barrel styled shotgun to fit a grenade launcher round. While a 40mm grenade would be ordinarily be too large for this system to be utilized (As demonstrated by the experimental weapon, based off of the M79, EX-41) effectively, the smaller and shorter round of the 25mm x 40mm grenade being much more useful in a shotgun, underbarrel styled mechanism.
To understand just how big the difference is between a 40mm and 25mm grenade, some basic mathematics calculations will be presented. The surface area of a 25mm "body" being 156.25 x 3.14(Pi) mm squared, compared to 40mm "body"400 x 3.14(Pi) mm squared, or very roughly, 490.625 mm squared compared to 1256mm squared, the ratio in area being that the 40mm round is around 2.56 times bigger around than the 25mm grenade. In terms of length, most of the 25mm x 40mm grenades are highly regulated, being created for use in semi-automatic weapons, being roughly 3.5 to 3.6 inches in length; compared to 40mm grenades, which can be anywhere from 3.89 inches in length for HE grenades to 5.272 in (133.9 mm) in length for smoke grenades. [1]. Despite lengths being 3.89 inches long for similar HE ammunition, (3.9 inches compared to at max 3.6 inches for 25mm grenades), the irregularly shaped heads of the 40mm grenade ammunition disallows for complete nose to tail contacts of the grenades, making the space between the nose and the nose of the grenade behind it to be nearly 4.5 inches for the 3.9 inch long grenades and over 6 inches for the longest style of grenades. This, coupled with the enormous stacked size of two 40mm tubes (I.E. the Barrel and the underbarrel tube) provides a good explanation for why such an easily interchangeable system for grenades and very similar shotgun shells were never implemented. Any 40mm underbarrel tube fed grenade launchers were simply too large and too heavy for common use at the time, despite their simple design creation.
Given a new grenade launcher round, that is literally designed to be stacked on top of each other and end on end with relatively little difficulty, and it's smaller size, makes it easy to understand why a very simply system that was never implemented before is currently being implemented on a mass production weapon.
