SOTAR AR15 Bolt Tail Gauge Set – BACKORDER


Available on backorder




If this item shows “Sold Out” our system WILL allow you to place a Back Order. Back Orders can take up to 4-6 weeks to ship. If you are not willing to wait, please DO NOT place an order. Orders cancelled within the projected Back Order window will result in a 20% Restocking/Cancellation Fee.

The Gauge Set includes:

2 Bolt Tail Ring Gauges (1 NO GO Yellow Color Coded, 1 FIELD Red Color Coded)

2 Containers (For Gauges)

1 Use and Care Instruction Sheet

U.S. Sales ONLY/No Export


If you’re interested in purchasing an Organizer Tray to hold all the Gauges we use, sells them:

The SOTAR AR15 Bolt Tail Ring Gauges Bore & Ga Set fills slots S & T on the Organizer Tray.


*We are NOT selling the Firing Pin Hole Gauges (Q in the Organizer Tray), Cam Pin Hole Gauges (P in the Organizer Tray), and Bolt Face Gauges (R in the Organizer Tray) at this time. We have open pre-orders for them that we. still have to complete. Those Gauges will only be available to Alumni unless I can find a manufacturer that can make them to our standards. I have tried about a dozen companies so far and none of been able to make them accurate enough for our standards.

*The Extractor Clearance Gauge (V in the Organizer Tray) can be purchased from Pacific Tool & Gauge

*SOTAR BCG 3 Bore & Gas System Gauge Set fills slots A through O, X, Y, & U on the Organizer Tray. They can be purchased from the School of the American Rifle Webstore.

*To do a thorough Bolt Carrier Group check you will need to acquire all the above, plus the following:

1) Bore Scope

2) Inch # Torque Wrench (One that can check breakaway/reverse torque, such as the Wheeler FAT Wrench)

3) Air Compressor

4) Headspace Gauges (.223 GO, 5.56 GO, & 5.56 FIELD)

5) 1″ Micrometer

6) Ejector Gauge

7) 8″ Caliper

8) Firing Pin Protrusion Gauge/Depth Gauge

9) Host/Test Barrel

10) Host/Test Upper Receiver

11) Carrier Key Straightness Gauge




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