Complete MK18 MOD 1 Clone Parts Build List

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 about $1,700 in 2025, you can build a functional MK18 with your preferred parts and upgrade it later to fully clone the original or match its look and feel as closely as possible.

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Make A MK18 Clone (Mod 1)

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 SSA Trigger - Trigger makes a huge difference

Also be sure to check out our best AR15 drop in trigger guide for more

• 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 machine shop, the difference is that the brand logo determines the price you pay.

MK18 Upper Receiver Build

• VLTOR or BCM Upper
• Bolt-Up System DD Barrel Nut Wrench
• Nickel Boron BCG
• DD RIS II 9.55" Rail (Must Have!) Or Geissele MK8 Rail
• DD 5.56mm 10.3" Gov Barrel
• 0.075" size Gas Block (unsuppressed)
• Carbine Length Gas Tube
• Radian Raptor Charging Handle
• SOLGW Forward Assist
• Surefire War Comp 556-1/2-28

Buy Factory MK18 Rifle Parts

Daniel Defense MK18 Upper RIS II

• 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.

Geissele MK16 10.5" rail

1:7 Twist 11.5" barrel

Surefire SOCOM 4 prong muzzle

MK12 Gas glock (.750)

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:

KAC RAS quad rail

KAC rail cover

Colt 10.5" barrel assembly 

FSB gas block

Required MK18 Build Tools

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