Reader Builds SA80

Reader James put together an Airsoft based SA80 and I thought you would like to see some pics of his process. He also wrote me the following in an email which helps explain a lot of the problems I had trying to put mine together.

James wrote quote;

This is a bitch to put together……

For the upper and the lower. I used a Star Airsoft cause the metal was
a bit thicker then the G&G. They all had issues with spacing.
Basically‚Ķ Here’s the deal.
You have to use an Airsoft body unless you have a massive press and dies.
But the airsoft guns all put the magazine too far forward and too far
apart from the trigger pack holes.
The airsoft guns are all too wide by about 2mm. And in some guns like
the G&G, the mag well is too short.
So basically… All uppers and lowers have to quartered and welded back
together. I have some images of how I did this and where I too material
I used the STAR because its was 2mm too long all in the area between the
Magazine and the Trigger pack so I could just take out 2mm right down
the middle, and the mag well accepted AR15 mags without modification.
However, its probably the least like the real steel guns. The G&G and
Army bodies of which I have 2 or 3 each could work, but you’ll need 2
guns to make 1 gun cause the length of the airsoft gun is spot on, but
you need to remove 2mm from the length between the magazine well and the
trigger pack. This is all based on were the trigger is and having an
actual trigger rod and a trigger pack. You know the spring guide from
the back of the gun will locate the back of the Barrel extension block
or trunnion. And then the bolt in battery will basically just pass the
Auto sear location.

In AutoCAD i made blocks of the pieces that I had for the real gun.
Those I wanted to fit absolutely and I found that those told me where
things had to go to make things work. Key points. Spring guide rod.
Trigger Pack holes. Length of bolt hold open level to catch magazine
follower. HK magazine. Auto Sear location on Trigger pack. Auto sear
cam on bottom of bolt. Bolt face with lugs in battery will tell you
where the barrel extension goes.
Length of trigger bar from trigger to trigger pack. Those all all
fixed elements which when placed will show you that airsoft bodies need
a shitload of work to make things fit right.

The G&G and Army bodies although they’ll look better need to have 2
airsoft guns each cut into 4 pieces, 1 cross cut and one length wise
cut. Because they don’t have the extra length.

Hope this is helpfull to you.!

Enjoy the pictures, there are a lot of them!

Project SA80 L85A2: Update


Lots of modeling in Fusion 360 and I got myself a 3D printer and started building my own stuff!

Here is the one I picked up Amazon Click Here

It is the Monoprice Maker Select Plus. I’m loving it.

Some stuff I have been playing with.

AR180C front sight base.


AR180B trunion.

SA80 L85A2 Airsoft bolt carrier

AR180S Hand Guard Retainer and fixture.

AR180B Upper Receiver



Project SA80 L85A2: Trunion Mock Up Part 4

SA80 L85A2 Trunion

Still making progress on the trunion and I am hopeful I can make it work.

Progress so far.

I even got the bolt carrier to sorta feed and eject. The green one is the latest version and I made a couple tweaks and I should have it printed by the time I get back in town.

Then a present showed up in the mail.

Two reasons I wanted to see this original AR180B trunion, first to actually measure the ID of the hole so I could find out the amount of press fit. Second I want to build some. Before I can do that I need to model it right?

How did I do?


Project SA80 L85A2: Bolt Carrier

Project SA80 L85A2

Had my daughter’s friend 3d print me some parts to mock up and it sure is easy to find your mistakes that way.

I have the firing pin retainer hole in the wrong spot as well as the charging handle. The outside dimensions are too big and the bolt carrier rubs on the inside of the upper receiver shell.

The design has been updated and I will get them printed up soon.

I also took the opportunity to model the original bolt carrier that I borrowed.

It is much slimmer than what I was building and it actually will ride on the airsoft guide rails since the holes are larger. This is where the frustrating part starts. When putting the original bolt and carrier in the gun it won’t strip rounds from the magazine. Either the original guide rails are lower in the receiver or the magazine is higher. I’m working on getting some more original parts to try in this shell and see where I am at.

I’m not giving up but I am having that nagging feeling that I might be stuck turning this into a .22LR instead of a 5.56.

Regardless of how it turns out I have learned a lot just from teaching myself Fusion 360 and from the study of these original parts.