Good friend of the site Oscar sent me an upper that another gunsmith attempted to remove the barrel on. He got it back from said gunsmith with the message that he was unable to remove the barrel and afterwords he was unable to tighten the barrel back up.
What many do not know is that the AR180B has a unique method of barrel retention and it is not at all obvious.
If we look at a bare trunion you will note that it has a large hole through the middle with a small step.
The barrel for this gun uses an AR15 barrel extension that is turned down and press fit into this trunion. That’s it! Nothing else. Just a press fit.
What happens then when the unsuspecting gun plumber puts a barrel wrench on the barrel and clamps that flat sided receiver in his vise? It makes funny noises and turns the extension in the trunion. Not good. Oscar mentioned that it shot terrible after he got it back and I suggested he send it to me for inspection. It didn’t take long to figure out my initial thoughts were correct.
Now how do I fix it so it is safe to shoot? I want to thank Oscar for being patient with me as I have had his upper for quite some time while I try to figure out what to do.
I settled on a shallow pin. I wanted it to not show unless you were looking for it and still be able to hold everything secure.
Sneaking the Tig torch in between the bosses was challenging but ended up with good penetration after I got the amperage dialed in.
So what is the right way to remove a barrel for the 180 Bravo? Use a modified reaction wrench. Do not put any twisting force on the receiver itself.
I now have everything needed to offer shorty conversions or to sell the parts outright if you want to roll your own. CNC machined from billet steel these new hand guard caps will retain the cut down hand guards on an AR180 or 180B. Shoot me a message through the contact form if you need more details.
Work progresses on the AR180S Pistol Grip and I am almost happy with the result but in between test prints I do other stuff to keep my mind busy.
How about a 9mm blowback version of the AR180? Sounds like fun! I think this could be an easier way to build a 180 since bolts and carriers are hard to source. I think this bolt could be made with less sophisticated machines and from less expensive steel.
The pistol that got me thinking about this some years back , the 9mm Australian Automatic Arms SAP 9mm.
What do y’all think? AR15 magwell adapter, Slightly modified. (Shown with my long neglected square tube prototype)
3D printed prototype bolt that uses an Uzi extractor and retaining pin.
Trunion design that has the barrel entering from the rear and utilizing a press fit. Although there would be room to fit a cross pin if needed.
What I am thinking it would look like. Maybe a DOE style hang guard retainer and front sight?
Got a 9mm barrel blank from Green Mountain and a chamber reamer from MidwayUSA.
Still have some work to do on the bolt design as I discovered it would not lock the hammer onto the disconnector. I really love being able to print some stuff and test fit it before making stuff out of metal.
Project 2? Selling some stuff to finance all these projects.
I have a very limited supply of Sterling 20 round steel mags for sale. $120 each shipped with tracking. PayPal gladly excepted if you kick in a bit to cover the fees.
Other spare parts as well, just ask for my price list.
Shoot me an email through the contact form if you are interested.