Weapons: 15mm and Point Five-Oh Recoilless

Version 2.0

15mm Recoilless Rifle and Pistol

“15mm Recoilless Rifle: A rifle-like weapon which fires 15mm projectiles and counters recoil by venting cold gas out the back of the weapon [or via vents in the side of the barrel]. Favored in zero-G combat.”
p.155 Transhuman Space 3rd Edition
The recoilless rifle is probably designed to use the same warheads as 15mm micro-missiles, but mounted on a more compact rocket motor to facilitate feed through a magazine. Each round is launched by a cold gas charge and then accelerated further by an internal rocket motor. The rocket motor also provides the means of course correction for guided and homing rounds. Alternate means such as fins and spoilers will obviously not work in airless environments.
15mm Recoilless weapons are more commonly encountered off-planet since it is more suitable for in zero-G combat than conventional caseless weapons. Ammunition is easily produced by minifac, so it is a popular weapon with space-dwelling isolationists.
Ammunition has the same warheads as 15mm micro-missiles but use 3d+1 pi++ for kinetic damage rather than 6d. A SAPHE projectile with Dmg 3d pi++ and a 1d-2 [1d-2] cr ex follow-up is also available.
Firing a round creates a soft hissing noise unlike a normal gunshot. Use the 4-yard line on the Hearing Distance Table, p. HT(4e)158. Obviously, firing in space makes no noise!
Acceleration is slower for 15mm recoilless rounds than for micro-missiles, so make their piercing damage by 1d+1 at 1 or 2 yards and by 2d+1 at 3 to 10 yards.
Guns (Rifle) (DX-4, or most other Guns at -2)
WeaponDamageAccRange (yards)Mass (lb)RoFShotsSTBulkRecoilCost
Recoilless Rifle 15mm3d+1 pi++4200/1,9008.5/2310(3)7-41$790
3d pi++
1d-2 cr ex[1d-2]
5d x2 imp (5)
1d cr ex[1d-1]
SEFOP4d+4(2) imp
Explosive damage is also incendiary.
Firing a 15mm recoilless round puts very little stress on the weapon. A recoilless rifle that is made from superior lightweight material and weighs only 4.25 lb has the same performance as a standard weapon but costs 50% more ($1,185).

15mm Recoilless Pistol

A large, but lightweight, pistol using the same rounds as the rifle is also available. The magazine-well is ahead of the trigger and also accepts the same 10-round recoilless rifle magazines. The magazine-forward configuration also puts a little more distance between the exhaust vents and the shooter's face.
Guns (Pistol) (DX-4, or most other Guns at -2)
WeaponDamageAccRange (yards)Mass (lb)RoFShotsSTBulkRecoil
Recoilless Pistol 15mm3d+1 pi++2200/1,9002/1.236+1(3)6-21
Holdout Recoilless Weapon 15mm3d+1 pi++0200/1,9000.25/0.1116-11
Spacers sometimes use these recoilless weapons to project lines and grapples. Under Earth conditions it can fire a grapple, harpoon, splat-piton. etc with a light line to 20 yards. Half this distance for a climbing rope.

Holdout Recoilless Weapon

The 15mm Holdout Recoilless is a single round loaded in a tube that can be concealed up a sleeve. Lacking a vent for the exhaust, it is not truly recoilless and may push the firer back if fired in microgravity.

Point Five-Oh Recoilless

This round is effectively the 15mm recoilless round reduced slightly in size in accordance with US laws against explosive rounds of greater than 13mm calibre. This redesign and the reduction in mass gives the round a slight increase in velocity, so in game terms it has the same performance as the 15mm round but cannot legally use rounds other than non-explosive ammunition. Damage becomes 3d+1 pi+.