Chuck at GunLab.net has been working on AR-180 uppers and has reverse engineered the trunion and has put up a very interesting article.
AR-180B Trunnion Design
I on the other hand, lacking any semblance of expertise in CAD took a differing approach when I reverse engineered my AR-180B upper.
Good friend of the site, Carl, sent me some square tubing that he has successfully used in his home builds. I decided to duplicate my upper using this material. It is much thicker wall than the original and I will have to shave this down at least on the bottom surface to get it to work with my lowers.
I did this for two main reasons. I wanted to refresh my skills on the mill as it has been many years since I last used one, and secondly, just to see if I could.
I made my first trunion out of 6061 aluminum just to test my measurements out and I have found that a few needed to be adjusted.
I learned a lot from this project and I find things like this much more rewarding than the usual beginners projects.
I will continue to tweak this until I am happy with it then I will start a new one using the first as a template. I think I will make the trunion out of 4140 unless y’all have any advice.
Some pictures that show what I have been up to for the last two days.
Some things to note if you attempt one of these yourself. The interior of the tubing is not perfectly square so some hand fitting will be necessary. The tubing spreads open once the bottom is cut. Some method of squeezing it back before welding would have to be considered. Lastly, all of this will be rendered moot once Chuck makes new uppers and flats available. Until then I will use this as a way to improve my machine skills and better learn my tools.
It looks like Chuck over at the GunLab has got his paws on an “In-The-White” AR-180 upper and if you know him like I do, that means we might be seeing some new uppers available soon.
I called him and we chatted for quite a while. He is hoping to make a run of these and offer them complete with trunion welded in but nothing on top. No dovetail, no rear sight. Perfect for those who want to build your own AR-180C flat top clone. He also is planning to make a run of flats.
I look forward to the day when the hobbyist like me, and many of you, can build our own AR-180 from scratch. That day may be closer than you think.
Reader Eric just sent me a message via the contact page and I have to say, it is something I have never considered before. I think it is a great idea. Here is the message he sent me;
From: Eric XXXX
Subject: Can we do a poll?
Hey guys, I was wondering if it was possible to put a poll up on the blog? Reason being, I’ve been communicating with Chuck at Gun Lab about making a bolt catch for original AR18/180’s modified to use mags with standard STANAG followers. I believe this will be a great opportunity for him plus provide us Armalite owners with a much-needed and way-overdue mod for our rifles. Simply put, no more “STANAG or Armalite” mags, just put a slit in a standard STANAG, PMAG or any of the dozens of other mags and it’ll function in the Armalite AND M16/M4/STANAG platform with a simple slit cut in the right-side mag body.
The poll would be simple…
“YES, I would buy this and maybe prepay”
“Yes, I like the idea but want to wait to see how it turns out (price, availability, quality)”
“No, I like being limited to overpriced, rare mags or modifying others to where they can’t be used in any other rifle”
Chuck might be on to one of the best mods to happen to the AR18/180 since it went to market. If we can put up a poll so he can see the interest, I’m sure he’ll move this up his “to do” list.
Thanks and thanks for the site and reviving the AR18/180 legacy!
~Eric, proud owner of a 1982 “widow-maker”
Please comment and let me know what you think of the idea.
I was alerted to this interesting full auto AR-180 conversion by a reader and I contacted the seller to get more information. I had assumed that all conversions used the same system as the AR-18 but my research shows that there are many different ways to get the job done.
This particular gun also brings to light the crazy gun laws that we have to deal with and in particular those surrounding full auto guns in Connecticut.
First lets see how an AR-18 worked.
You can see in this picture that the upper receiver has two tabs that retain the auto sear. A link is attached to the sear that rides along the bottom of the upper and is tripped by the bolt carrier. The sear acts upon the rear of the hammer. The hammer is different than the one used on an AR-180 as is the disconnector, bolt carrier, and firing pin.
This conversion goes about it in a completely different way.
This conversion is on a Howa AR-180 and it has a sear that acts on the front of the hammer. It appears to have a pivot added to the front of the fire control box and you can just make out the pin location in the picture above. The sear has a tail that is tripped by a piece that was welded on to the bolt carrier. It uses all the original 180 fire control parts with the exception of the disconnector and the safety. The 180 firing pin is also retained.
I wonder if this is how the Widowmaker conversions were done?
Now for the Connecticut twist on this story. It appears that those who drafted their assault weapons ban tried to get machine guns classified as assault weapons and in doing so, left the door open for guns that are full auto only. You can’t own a registered select fire weapon (one that fires Safe/Semi/Full) but you can have a papaered Full auto machine gun (Safe/Full). This gun is one such animal. For those that live in other states, it can be converted back to a select fire configuration.
Please feel free to comment about any conversions you have come across. I think this is a very cool part of the history of the AR-180.