So after looking through most of the books I own I can not find the rules for a weapon being stripped down. I only noticed this when I found the entry for the Ordo Xenos Inquisitor (Nemesis) with 2 stripped down conversion beamers that are counting as pistol weapons. Is this listed somewhere that I am overlooking or is this a basic weapon upgrade that they just described as stripped-down? Thanks for any directions to find the solution to this question.

There is the "Compact" weapon upgrade that shrinks a weapon class by one, but it doesn't work on Exotic weapons. I assume these are custom Inquisition weapons probably enhanced by a Jokaero.

Compact doesn't change the weapons size category, it simply negates the -20 penalty for one handing a basic weapon and allows concealment tests a bonus.
Micro is a far superior upgrade and downgrades a weapons size 1 category to a minimum of pistol.

I'd imagine they are closer to Micro than Compact, with an Inquisition weaponsmith having stripped out some of the bulky parts and 'unnecessary safety features'.

Also known as "Plot Guns" The 41st Millennium is full of unique stuff pulled out of thin air to make a character special/awsome.

Cool, Just wanted to make sure that a weapon quality/upgrade didn't exist that made this creation easier. I figured it might be just a random creation but just needed to check. Thanks for the answers!

Conversion beamers exist in Deathwatch, but they are astartes grade and ancient weapons at that... i doubt the rules port over easily.

They're also in Dark Heresy's Daemon Hunter and Faith and Coin, but they're both Heavy weapons in there.