In this ultimate build guide, we put together a complete MK18 parts list for anyone building a SBR (NFA) or a pistol (non-NFA).
For around approximately $1500, you can build a bad ass MK18 with exact parts you want, and you can also upgrade it later.
Let's check them out...
MK18 Lower Receiver
- Spike Tactical Lower (Any receiver will do)
- DD Stock/Grip Set - Use this if you want a Daniel Defense look
- Magpul UBR 2.0 (Buffer tube included) or VLTOR EMOD - Very sturdy stock
- Geissele SDE Trigger - Trigger makes a huge difference
be sure to check out our best AR15 drop in trigger guide
- Anti Walk Pins - It prevents trigger pins from walking out after high volume use
- Geissele Super 42 Braided Buffer Spring
- H2 Buffer (Normal Use) or H3 (Suppressed)
- Geissele Lower Parts Kit - It works
- BCM AR Trigger Guard - It works just fine
- Magpul BAD Lever - Enables firing hand bolt lock / release
- BCM Mil Spec Buffer Tube - It works
Most receivers are made at the same factory (Contiental Machine Tool) as any others, the difference is that the brand logo determines the price you pay.
Our favorites upper & lower receivers:
Some has very slick billet cut design to make your MK18 stand out more than the standard A2 upper.
Please check out our upper receiver guide for more info.
MK18 Upper Receiver Build
Check out MK18 weapon light configs here
- VLTOR or BCM Upper
- Bolt-Up System DD Barrel Nut Wrench
- DD factory BCG or Nickel Boron
- DD RIS II 9.55" Rail (Must Have!) Or Geissele MK8 Rail
- DD 5.56mm 10.3" Gov Barrel
- 0.070" size Gas Block (unsuppressed)
- Carbine Length Gas Tube
- Geissele Airborne Charging Handle
- Forward Assist
- Surefire War Comp 556-1/2-28
Buy Factory MK18 Rifle Parts
Daniel Defense MK18 Upper
The Daniel Defense MK18 with the DD RIS II handguard rail is the real deal.
- Battle proven 6 bolt bolt-up system securely attaches the handguard to the upper receiver
- 2 piece design accepts M203 grenade launcher without additional parts
- Seriously made for war
- 6061 T6 aluminum, durable & lightweight
- Free float system, increases accuracy
- Continous top rail
PSA 10.5" 5.56 NATO MK18 Upper Clone
The Palmetto State Armory 10.5" 5.56 NATO upper is another great option to clone a MK18 style rifle. The upper features forged 7075 T6 mil spec aluminum with hard coat anodized for durability and corroision protection.
Yes it comes with a bolt carrier group. All for under $400
MK18 Mod 3
The MK18 MOD 3 is about having a 11.5" barrel and the MK16 rail & better suppressor performance. The US Army calls it the MK18 CQBR UGRI.
The upper is improved to prevent gas blow back in suppressed mode, the MK18 Mod 3 also comes with the PRI M84 charging handle.
MK18 MOD 0
The MK18 Mod 0 was one of the earliest configurations based on the M4A1.
It was simply a shorter M4A1, and it features the classic KAC M4 quad rail plus the fixed A2 front sight post.
If you clone this upper just for the aesthetics, it's quite simple. You can buy affordable Aero Precision 10.5 complete upper then change the rest as you desire or build from scratch:
Colt 10.5" barrel assembly or FN 10.5" barrel
MK18 Build Tools Required
We highly recommend using these tools to assemble the upper receiver at home, or take it to a gunsmith.
Midwest Industry Reaction Rod - It prevents receiver shear while torquing barrel nut and muzzle
Vice Clamp (Heavy) - Holds everything in place on a work bench
Work Bench - Must be able to handle torque (Recommend something sturdy)
1/2" Drive Torque Wrench (Ft lb) - Use to apply exact torque