Selecting Between 6061 Aluminum Alloy and 7075 Aluminum Alloy For Your AR-15 Build
Written by: Aaron Henderson
When building your AR15 and selecting components, an inevitable question will arise in regards to selecting between 6061 aluminum vs 7075 aluminum alloy. When discussing AR15 parts, “aluminum” is commonly used as a short form of what is actually aluminum alloy. Aluminum alloys are primarily made of Aluminum “Al” combined with a variety of alloying agents combined such as Zinc Zn, Silicon Si, Magnesium Mg, Tin Sn, Copper Cu and Manganese Mn. There are significant cost and physical differences between 6061 and 7075 aluminum alloys and 7075 is considered an upgrade. Customers want to know if it’s worth paying for aluminum alloy material upgrade costs vs putting their funds into something else like a better trigger or stock. To make an informed choice, I’ll explain some differences.
Aluminum alloys are always a blend of several metals with a set goal in mind. 6061 aluminum primarily uses silicon and magnesium as alloying metals. It is known as a “jack of all trades” alloy for it’s hybrid blend of characteristics like excellent weld-ability , malleability, corrosion resistance and strength at a low material cost. Like many blends though, when you maximize one aspect, you “rob Peter to pay Paul”.
7075 aluminum alloy mainly uses zinc as the alloying agent of the aluminum. It also has a higher percentage of magnesium, manganese and copper than what is found in 6061 alloy. This 7075 alloy has the strength of many types of steel and is stronger than 6061 while maintaining the lightweight goal of aluminum. 7075’s trade offs are a lower corrosion resistance than 6061 and higher cost. 7075 is commonly used in military aircraft, boats, and auto parts.
To decide on the part for your AR15 build, I would consider where the part is being used, possible cost trade offs and what your needs are. 6061 aluminum has been used since the origination of the AR without fail and is a “tried and true” choice. Very few places in your AR will ever see a need for the superior strength that 7075 aluminum can provide. Areas that do require the highest strength such as the barrel trunnion are high grade steel. Generally speaking, forged 6061 is more than adequate for your upper and lower receivers. If your AR may be used for a “Butt stroke to the head” series, then investing in 7075 for the buffer tube may be a wise move that justifies the added expense. The ALG Defense True 7075 Buffer Tube is a nice option at an affordable price. If your budget is limited though, I would always recommend a trigger upgrade investment over the standard mil-spec lower parts kit trigger more than any other single cost upgrade. 6061 aluminum is more than adequate for the AR15 and the vast majority of civilian AR15 users. For hard military use, and/or the guy for whom “money is no object”, then 7075 aluminum is a superior option in your AR15.
About the Author
Aaron Henderson, Owner of Valhalla Tactical Supply