Lorenzo's Artifact gun

Lorenzo's Artifact gun is a unique weapon in Fallout 4.

Characteristics
This weapon is actually a unique gamma gun mod installed in a regular gamma gun. The effect of the mod is that the gun fires unique projectiles that may significantly knock back enemies well above and beyond the normal stunning effect of a gamma gun, in addition to doing a different type of damage. One can remove the unique mod and install it into a different gamma gun, which includes legendary gamma guns as of patch 1.4.

Unlike the vast majority of radiation weapons, the radiation damage dealt by Lorenzo's Artifact is pure damage; it does not do radiation poisoning (in other words, it does not give rads to hit targets). Although it is still affected by radiation resistance, it's not affected by radiation immunity; since radiation immune targets have 0 resistance to pure radiation damage.

While numerically a gamma gun has a higher "damage," the gamma gun and Lorenzo's Artifact have very different mechanics. The gamma gun has a core explosion component but is mostly intended to do its damage in the form of rads, which is effective based on the enemy's maximum health. Lorenzo's Artifact trades that off to do direct, unconditional damage. As a result, there will be cases where Lorenzo's Artifact's "lower" damage will actually be much more effective than the gamma gun, and there will be cases where the gamma gun will be more effective. See radiation weapon for a more detailed discussion.

When equipped with the electric signal carrier antennae, this weapon does a dramatically different set of damage spread across multiple damage types, generally boosting its overall usefulness against most enemies; it can furthermore be charged to do even more energy damage.

It is possible that the weapon was supposed to be non-lethal, as Jack Cabot states when giving it to the Sole Survivor, saying that it won't kill people, but the Sole Survivor might find it useful in other ways.

Variants

 * Gamma gun
 * Zeta gun

Location
Reward from Jack Cabot for completing the quest The Secret of Cabot House.