This is a continuation from the 80% lower I machined and had custom laser engraved by the guys at https://www.customardustcover.com/
More details on the machining process of the 80% receiver visit:
Although there was a mistake or two on the lower receiver engraving I have made it work.
Special thanks to the people at Adams Arms, OpticsPlanet.com, and Wilson Combat. They all hooked me up with a discount on the parts.
Wilson Combat's packaging was excellent and the Burnt Bronze treatment matched my lower receiver perfect as well. 1:7 Twist Stainless barrel with a Gas block hole cut in the pistol location for reliable subsonic use.
To the right, I was testing my lower with my Huldra Mark IV upper that in 5.56. The lower with its trigger job works absolutely terrific, but now we get to make the rifle that this lower was intended for.
This barrel is special as it is 16 inches and specially machined with a pistol gas port allowing reliable subsonic semi-automatic operation. For the anti-gun extremist out there Boogie Boogie boo!
My Yankee Hill QD attachment for the Suppressor still on its way awaiting ATF to process the 200.00 tax stamp. That takes 6 months to a year give or take. Unconstitutional as well mind you. Important to note that you will pay the full cost of Suppressor then it will sit in your FFL Dealer's Safe till the tax stamp is processed. ATF will take their sweet time processing that stamp unless you one of the lucky ones that happen to get processed quicker. I have a titanium Yankee Hill I found for 50% off. Lucky me!
Before the full final assembly, I like to test fit all the parts.
Everything appears to be a fantastic fit.
Now to get working. I got to looking at the tools I had and I was missing the right size crowfoot wrench, so being the fabricator I am I made a workaround
Now that I have my barrel nut torquing tool made I can continue.
For improved accuracy, I lapped the upper receiver.
I did this process by hand. It takes material off pretty quick. I was using a 220 grit lapping compound.
The lapping tool you see here is bought at Brownell's.
After a few test fittings, we are ready to torque between 35 - 85 ft-lbs.
I came in about 45 ft-lbs.
Lucky for me that the Adams Arms rail came with barrel shims so you can index the nut without going crazy with the torquing. I ended up using only one shim on the barrel extension.
Each receiver barrel combo can very in torque or shim requirements.
Now I will be installing the Adams Arms Adjustable Micro Piston Kit.
Here you will need to add a bushing into the upper receiver for the piston rod to feed through.
Notice there is a tapered end and a flat end of the bushing.
Apply some Polymer grease to the tip of the rod and the bushing.
Make sure to place the taper end up on the install rod. The grease should hold the bushing in place as you carefully install.
Use a hammer to install carefully. Lightly tap into the place where normally the gas tube from a direct impingement system would come through the upper receiver.
when looking from the other side you can see the bushings position.
Checking the fit of the Piston system.
Gas Block torquing. 87 inch-lbs for the Adams Arms Adjustable Micro Gas Block.
Next, we need to install the Yank Hill Quick Detach Muzzle brake that will be for the Suppressor that is awaiting pick up due to ATF's Unconstitutional TAX stamp.
Shims are provided with the QD for indexing the barrel to the appropriate location. 35 ft-lbs.
Now since this gas block is way back you'll need a long flat tip screwdriver for adjusting the gas block. or you can try pushing through the holes on the rail. I already had the long screwdriver in my toolbox.
The final product, one kick but 300 blackout rifle.
The rifle above the 300 is my Huldra Mark IV, which was the first piston system I dealt with. I was hooked from then on. After dealing with my M16 for years in the Army, I wanted to make something better.
Thanks again to the people at Adams Arms, OpticsPlanet.com, and Wilson Combat. They all hooked me up with a discount on the parts.
