The 10mm pistol is one of the first weapons found inside Vault 111 (after the security baton), located in the overseer's office. The pistol itself does reasonable damage and is great as an early tier weapon. It also allows for a reasonable amount of modifications that further emphasizes its versatility. However, despite being provided with a substantial amount of ammunition in Vault 111, ammunition in the early portions of the game afterward is rare.
Hub 360, in the DIA cache that may be accessed from a side alley fire escape and collapsed building debris.
Can be bought from most weapon vendors and usually from general traders.
Despite the long barrel modification being considered the "standard" for the weapon, the majority of 10mm pistols spawned in the world use the short barrel. This is an anomaly shared with the .44 pistol and the Deliverer.
The two 10mm pistols found in Vault 111 both share a rare quality, in that whenever they are picked up, they will automatically be equipped, replacing the currently equipped weapon. This occurs even if the weapons are modded and renamed.
When the standard magazine mod is detached from a weapon, that mod cannot be re-attached to any 10mm pistol (including the one it came from). In order to remove a different magazine type off a 10mm pistol, either a new standard magazine must be crafted, or a different magazine type must be swapped on to the pistol in order to obtain the desired magazine mod. [verification overdue]
Modifications: long light barrel, standard grip, standard magazine, reflex sight
Modifications: long light barrel, comfort grip, large magazine, suppressor
Modifications: long ported barrel, comfort grip, standard magazine, reflex sight, compensator
Modifications: long barrel, sharpshooter's grip, standard magazine, standard sights
Modifications: long ported barrel, sharpshooter's grip, standard magazine, recon scope, suppressor