80 Lower Receivers
Although it’s a little difficult to make out in some of our pics, these 80% Lowers are marked with “SAFE” and “FIRE” on both sides. In the future we may consider a pictogram design instead.
We designed our proprietary Gen2 Billet Lower Receiver to have a custom tapered Round Stock Mount shape. We cut in some extra reliefs on each side of the Stock Mount just above the Take Down Pin hole so that our Stock Mount blends well with standard Forged Uppers or any Billet Upper that has a “Light Bulb” shape at the rear of the Upper.
We originally started our Billet Lower Receiver design as a straight-forward clone of an OEM Forging but with an Integral Trigger Guard. But then we realized that as a custom firearms manufacturer, we wanted to allow plenty of options for our customers plus flexibility in our products. After some thorough research, we discovered that a large number of aftermarket Trigger Guard designs are currently available, and we will want to add our versions to the mix in the future as well. We decided that with so many Trigger Guard options available, plus an Integral Trigger option, that would provide plenty of flexibility for all of our customers.
Billet vs Forged
We started making our Lower Receivers from Forgings and quickly learned that they are really difficult with which to work. From a machining stand point, most pieces are way out of spec. We found several examples that were 0.060-0.070″ under size for the width of the part alone. This makes everything “thin walled” when finished machining – the mag well, the FCG pocket, etc. Plus they seem to be all over the board on tolerances (Height, Width, Thickness) so to set a machining program to one to get everything correctly positioned and machined had to changed again on the very next part.
We went to Billet machining fairly fast as with that method we have way more control and can make a much more solid, robust and accurate part. We do however, look forward to a time when we can make our Uppers and Lowers as castings. But you have to be a fairly large company to be able to pay for the tooling involved.
6061 vs 7075 Aluminum
To us – six of one – half a dozen of another. From strictly an engineering standpoint, both are over engineered for this application and will work just fine but if you look on the various gun forums on the internet, you’ll see many people claiming to be the ‘best qualified’ to decide the question. We believe that our customers are the best qualified to decide what they want, so we made the material an option. The only true difference for us as a manufacturer is the cost of the material, which 7075 is a bit more expensive due to being way less common – the aerospace industry doesn’t really use it. The machining characteristics appear to be the same between 6061 and 7075 since both are Aluminum and are being machined (like butter) with HSS Drills and Carbide End Mills.
Many customers request that their 80% Lower be Anodized, so we made sure to add that option. When you finish machining the Lower, you break the seal of the Anodizing that was done prior to your work. You have to do one of two things then – either strip it completely and reseal the whole thing again, or just ‘let it go’. We’re thinking at this time that most customers just ‘let it go’ as long as it still looks finished from the outside when assembled.