There seems to be quite a lot of weapons with nice mods attached that end up being never used for one reason or another. So my idea is simple: let players extract one mod from the weapon, but it requires high munitions skills, some tools, and will destroy the weapon in the process.
This would create a secondhand market for mods, but won't crash the price too far (hopefully) as it does consume the weapon, and gives gunsmiths more possible avenues of RP and even revenue.
And declutter the 2nd hand heaters market as a bonus.