- Kel-Tec
- Keng's
- Kershaw
- Kestrel
- Keystone Sporting Arms
- Kick-EEZ
- Kimber America
- Kinetic Development Group, LLC
- Kleen-Bore
- KLVR Co
- Knights Armament Company
- KNS Precision, Inc.
- Konus
- KORE Essentials
- KRISS USA, Inc
- L.A.G. Tactical, Inc.
- Lancer
- Lancer Systems
- LanTac USA LLC
- LaserLyte
- LaserMax
- LBE Unlimited
- Leapers, Inc. - UTG
- Legend Outdoor Gear
- Leisure Carry
- Les Baer
- Leupold
- Liberty Precision Machine
- Limbsaver
- LIVE FIT
- Live Free Armory
- LMT
- Lockdown
- Lone Wolf Distributors
- Lorcin
- Lucas Oil
- LUCID OPTICS
- Luth-AR
- LWRC
- Lyman Products
- M-PRO 7
- Mace Security International
- Maglula ltd.
- MagnetoSpeed
- Magnum Research
- MagPod
- Magpul Industries
- Magpump
- Magtech Ammunition
- MagView