The full rules for enchanting magical items can be found in the Wild Adventure rulebook, pp. 48-59.
Eternal Bullet [Dedicated Magical Item]
Cost : Usually not for sale.
Description: This strange item appears to be a golden bullet in a rune-inscribed metal casing, though as a matter of fact the cartridge is all one piece and cannot actually be fired. However, by placing this “bullet” into a firearm capable of firing that kind of ammunition, that firearm gains the ability to make a magical attack once round by pulling the gun’s trigger, essentially making this object an everlasting round of ammunition.
It is unknown who first made these unusual items, and very few exist, though there seems to be some connection to the arts employed by gun mages, though most eternal bullets cannot accept rune shots. Interestingly, some eternal bullets have been crafted in the likeness of the silk or paper bag rounds of old (though they are still a single piece of rune-inscribed metal), suggesting they were made before the advent of metal casings.
Special Rules: Once per round, a firearm that has been loaded with an eternal bullet can mage a magic attack with the same attack modifier, RNG and POW as the gun it has been loaded into, though this magic attack does not have an extreme range, RNG:SP or AOE, even if the gun would normally have these traits. The attack roll for this magic attack is made using POI plus the required military skill (i.e. Pistol, Rifle, Light Artillery or Heavy Artillery) and benefits from all usual modifiers to ranged attacks (e.g. aiming or bipods) except for non-magical equipment, abilities or effects that change the gun’s RNG (like scopes).
Firing an eternal bullet from a non-magelock firearm will slowly erode that firearm over time (see “Imperfect Instruments” in IKKNG, p. 244). Firing an eternal bullet from a mechanikal firearm that has not been fitted with a runic conduit (see MIKG1, p. 23, and MIKG2, p. 16) is extremely dangerous and risks an explosive disjunction (Roll 1d6 when making an attack with such a mechanikal firearm; on a result of 1 or 2, the attack fails and the mechanikal firearm explodes: Place a 3” AOE on the character who attempted the attack, who suffers a damage roll with a POW equal to 14 plus the firearm’s rune points value. The AOE becomes 4” if the firearm has a rune points value of 3 or 4, and becomes 5” if the firearm has a rune points value of 5. All other characters in the AOE suffer blast damage. The eternal bullet and the mechanikal firearm are completely destroyed in this disjunction event).
Some eternal bullets have been specially made to accept rune shot spells, though their capacity to do so is limited compared to standard rune bullets. Most eternal rune bullets can only accept rune shot spells with a total COST of 4, though some rare ones accept spells with a total COST of 6. If a gun mage attempts to cast more rune shot spells on an eternal rune bullet than it can accommodate, any spells that exceed the bullet’s capacity simply fail (though the gun mage must still pay those spell’s COST).
An eternal bullet can only be fired by the type of firearm it has been made for, and cannot be reworked to fit any other type of firearm. Additionally, as the attack granted by an eternal bullet is a magic attack, it is subject to all abilities that affect magic attacks (e.g. the spell ward rune in IKRPG, p. 286).
Prerequisite: Military Skill 2 (determind by the firearm the eternal bullet has been crafted for), Craft (gunsmith) 2, Lore (arcane) 2 for “standard” eternal bullets. For eternal rune bullets, the enchanter must also have the Craft Rune Shot ability (see IKRPG, p. 160); for an eternal rune bullet that can accept rune shots with a total COST of 6, the enchanter must also have Lore (arcane) 3.
Fabrication: The material cost for the shell for an eternal bullet is 15 gc. Attunement takes 6 hours and requires a successful ARC+Lore (arcane) roll against a target number of 14. Inscribing the runes takes two weeks and requires a successful ARC+Lore (arcane) roll against a target number of 14.
The material shell for an eternal rune bullet costs 45 gc. Attunement takes 12 hours for an eternal rune bullet that can accept rune shots with a total COST of 4 and requires a successful ARC+Lore (arcane) roll against a target number of 16. Attuning an eternal rune bullet that can accept rune shots with a total COST of 6 takes 15 hours and raises the target number for the ARC+Lore (arcane) roll to 17.
For a “standard” eternal rune bullet, inscribing the runes takes four weeks and requires a successful ARC+Lore (arcane) roll against a target number of 16, but takes five weeks and requires a successful ARC+Lore (arcane) roll against a target number of 17 for eternal rune bullets that can accept rune shots with a total COST of 6.
Comments welcome, as usual.