An ultralight AR-15.
How to build AR-15 2kg weight, without a registration and SMS.
It was one of the most interesting projects I’ve ever had. An AR-15 owner wanted to get an ultralight gun for hunting.
This hunting style connected with the long walks, therefore, the weight was very important. It was necessary at carbine mass decreasing to save it maximum abilities without reliability loss in work. That’s why the forward assist and the ejection port/dust cover were kept. Also, for the same reason were used a plastic pistol grip and stock, not aluminum ones, which despite lower weight are cooled faster in winter and “chilling”.
Reconfiguration of the base carbine automatics.
The base was carbine Zbroyar Z-15 in caliber .223 / 5.56h45 mm. with a 10.5” barrel. The initial weight was 3.3 kg.
The main feature of this carbine “from the box” was such an automatic set-up, so it didn’t work without flash suppressor - the used cartridge case hasn’t been extracted. Despite the fact that this carbine is used only with a suppressor, it was decided to make it work without a muzzle device, generating back pressure. This was achieved by using a lightweight bolt frame and light buffer. As a result, despite of a slight decrease of dirt resistance, the automatic system began to work steadily even on not "hot" cartridges and without a muzzle device, generating back pressure. Also, an interesting feature of this project was that it used a Franklin Armory binary trigger. This trigger, in addition to the usual mode "1 press on the trigger - 1 shot", has a shot mode on squeezing the trigger and shot when it is released. I note, that this solution doesn’t turn the carbine into an automatic one.
Struggling the overweight.
Next stage is the struggle for mass reduction. It was about every extra gram. among other things, almost all steel parts and controls have been replaced with aluminum alloy or titanium.
There is a list of these changes below:
- Titanium firing pin;
- Aluminum ejection port/dust cover;
- Aluminum ejection port/dust cover pin;
- V Seven Aluminium forward assist;
- V Seven Titanium magazine release button;
- V Seven Titanium Buffer Retainer Pin;
- V Seven Titanium Castle Nut;
- V Seven Titanium endplate;
- V Seven Titanium gas block;
- V Seven Titanium Grip Screw;
- Battle Arms Titanium pins;
- Seekins Precision clamp;
- Seekins Precision Enhanced Bolt Catch.
At the time of the primary assembly of the carbine, with an ultra-light forend made of aluminum alloy SLR, its weight was 2260 g. Over time, the magnesium V Seven forend appeared on the market and, of course, such a forend was installed. For understanding the weight difference - magnesium forend is lighter than aluminum one that the lightest on the market for 95 g! (130 g. against 225 g.).
Also, Strike Industries charging handle, Hogue pistol grip, Mission First Minimalist stock (the lighters among the plastics stocks) were mounted.
The final result for today was the index of 2070 grams! And 2680 grams, with a custom titanium suppressor, an EOTech sight (without a protective case) and backup mechanical sights.
How it eventually works.
The cartridges by ABR (77grams) were matched for this carbine. During the shooting group test with this cartridge, stable density in 1 MOA was shown, that is a sufficient practical indicator along with bullet efficiency.
At reliability shooting test, the carbine worked 300 shots without any issue, cleaning and greasing.
I wish to say that it’s not the end yet. There will be some replacements in the future, such as the trigger pins will be replaced to titanium ones, the barrel's contour will be a slightly different, the carbine will be painted in an original way.