For people doing Gun Smith: Part 1

You can get the remington choke from the Mechanic trade for the "MP-133 Tactical", costing two pliers elite and one screwdriver, the plastic pistol grip can be bought from Jaeger level 1 and you can usually get a shotgun with the "strut" attatchment from a shotgun sold by Fence. The final piece (the tactical laser) can be bought from Skier level 1.

Edit: Turns out you don't actually NEED the strut attatchment for the quest, you can use the custom plastic forestock that comes with the "MP-133 Tactical", just need to attach the laser to it! -Thank you Friend_Besto for the comment!

Edit 2:

You can get a GK-02 muzzle break as well and one of the L1 traders sells the adapter, works the same and it's way more common

-Thanks Corzappy for the extra info!

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