I like to hop between safe houses and check the vendors between resets, and since the game doesn't tell you what the vendors in the safe houses are from the map I decided to drop by each and record what vendor is where. I figured I'd post it up here to help you too. I've organized them by the relative level of the area.

Camp Hudson - Weapon and Gear Vendors
Base of Operations (Pensylvania Avenue) - Everything
Hudson Yards - Weapons Vendor
Garment District - Gear Vendor
Tenderloin - Weapons Vendor
Hell's Kitchen - Gear Vendor
Times Square - Gear Vendor
Clinton - Weapon Vendor
Flatiron District - Gear Vendor
Gramercy - Weapons Vendor
Stuyvesant - Gear Vendor
Kips Bay - Gear Vendor
Murray Hill - Weapons Vendor
Turtle Bay - Gear Vendor
Midtown East - Weapons Vendor

DZ06 - Dark Zone Special Vendor (Set pieces and set piece blueprints only, for DZ cash)
DZ05 - Dark Zone Weapon Mod Vendor
DZ04 - Dark Zone Gear Mod Vendor
DZ03 - Dark Zone Weapons Vendor (Sells Valkyria, unique SMG, requires 90 DZ rank)
DZ02 - Dark Zone Gear Vendor

Map created by McKillem

Accuracy
The cone of fire of your gun, depicted by the reticule expanding and contracting. How well it maintains accurate fire in full auto and recovers and returns to full accuracy after firing.

Stability
The recoil of the reticule as a whole, how much you have to 'fight' it while firing on full auto.

Initial bullet stability
How much recoil the first bullet fired has. Works great for single shot weapons or for more accurate burst fire. Not so much for full auto or LMGs.

Horizontal stability
The side-to-side jumping during recoil, resulting in more straight-up and therefore controllable recoil.