CS12-80 80% Combat Shotgun Receiver Set – Batch #2 – PREORDER – CLOSED

Second Preorder Closed.

Read the complete description for pricing and kit contents, as the available options have changed.



Second Preorder Closed.

What is it:

The CS12-80 is a hybrid combat shotgun which combines the rugged reliability of the Mossberg 500 12ga pump action with the ergonomic controls and ease of handling of the AR-15.

Our receiver kits are compatible with all lengths of current production Mossberg 500 & 590 Shockwave magazine tubes and barrels.

Some or all older production Mossberg 500 and 590 or even Maverick 88 parts kits may work as well, but have not been tested and are thus NOT guaranteed to fit or operate properly.

And yes, since it will have never been a shotgun before you get it, you could use this receiver set to build a “firearm” using a 14″ Shockwave barrel and an AR15 buffer tube mounted arm brace.

What’s Included:

80% complete Upper and Lower Receivers (NO ENGRAVING except for S/F markings on lower)
All Required Hardware to Assemble the Receivers themselves (cap screws, allen nuts, dowel pins, etc)
Take Down Pin Assemblies
New Firing Pin
New Firing Pin Return Spring
New Action Lock, Pivot Pin, & Spring
New Action Lock Control Button (easily swapped to suit a right or left handed shooter)
Wolff Extra Power AR15 Hammer Spring

What’s NOT Included (but you’ll still need):

ALL the parts from a stock 12ga Mossberg 500 pump action shotgun except for the following:

original receiver
trigger pack assembly
take down pin
firing pin
firing pin return spring

The following AR-15 parts:

pistol grip
mil-spec semi-auto fire control group (trigger, hammer, disconnector, pins, and springs)
safety selector
safety selector detent & spring
buffer tube (A2 for fixed stock, M4 for adjustable stock)
receiver end plate (not needed for fixed stock)
buffer tube jam nut (not needed for fixed stock)
buttstock (A2 fixed or M4 adjustable)

The following Jig & Fixture Plates (available for sale as a separate kit, not required if you use a milling machine to finish receivers):

Jig Plate Set (Jig & Cheek plates that you can use to finish the machine work on the receivers using a trim router and a hand drill)

The following cutting tools (available for sale as a separate kit):

1/2″ OD x 1/2″ Length of Cut Top Bearing Flush Trim router bit (shank sized to fit your router)
1/2″ OD x 3/4″ Length of Cut Top Bearing Flush Trim router bit (shank sized to fit your router)
5/32″ twist drill
3/8″ twist drill
0.257″ (Letter ‘F’) twist drill

What’s Left to Machine:

Two sets of denial islands inside the upper receiver
Entire FCG pocket in the lower receiver
FCG cross holes for trigger/hammer pins and safety selector in the lower receiver
Cross hole for Bolt Lock pivot and actuating pin in the lower receiver
Take down pin holes must be enlarged after all other work is finished to allow the take down pins to slide through smoothly




PLEASE NOTE:  This is a PREORDER.  None of the parts you are purchasing have been machined yet, and will not be machined until after the preorder has closed (or at least gotten close enough to done that we can get a good idea of how many receiver sets to make).  Once production starts, all of the money raised here will have been spent on material and perhaps even machinery/equipment to produce the parts with.  As such, once production starts, there can be no cancellations or refunds.

We will deliver parts to customers as they are made, on a first purchased = first shipped basis.  Be prepared for delivery to take five or six months (after the preorder ends), maybe more if something gives us trouble.  We will post production updates on the blog here as time goes on, to keep everyone in the preorder apprised of what is happening.

Additional information

Weight 5 lbs
Dimensions 11 × 8.5 × 6 in
Choose Kit Options

Receiver Set Only, Receiver Set + Jig Plates, Receiver Set + Jig Plates + Cutting Tool Kit