More AR180B Prototype Parts Found in the Wild

I picked up what was sold as an AR180 trunion but I could tell from the pictures that it wasn’t exactly that.

AR180 trunions are not flat on the side. They are forged into a rough shape that leaves the sides with a relief.

Photo courtesy of

This newly discovered trunion is built like the ones used in the AR180B.

What made the AR180B trunion unique was the fact that they turned down a regular AR15 barrel extension and pressed it into the trunion shown above. This was obviously a cost savings measure.

What is so cool about the newly found trunion is it proves that they didn’t start off with that in mind. They were going to make them one piece.

The final piece of evidence that shows this was not built for the AR180 but instead the AR180B is that it will not head space with an original barrel but will with an AR180B barrel.

It’s too bad that this wasn’t used in the regular production AR180B. It certainly would be more durable when barrels needed to be swapped out.

One Reply to “More AR180B Prototype Parts Found in the Wild”

  1. Rick, Too bad you can’t put this trunnion into production with new made uppers.

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