If you’re looking at the opportunity to build your own rifle at home, among the other things you’ll need are a lower parts kit, an upper parts kit or an assembled upper, a jig to complete the lower, and of course, the lower blank itself.
Unfinished lowers are typically referred to as “80% lowers,” or “receiver blanks,” or, to people that don’t know anything about guns, as “ghost guns.”
But let’s stay on topic. Generally speaking, there are two broad classes of lower receivers, being forged lowers and billet lowers, both of which are made from aluminum.
But the type of aluminum can vary, as does the manner in which the lower receiver blanks themselves are created. Here’s a quick primer on what you need to know.
What Are Forged Lowers?
Forged receivers are also sometimes referred to as “mil-spec” lowers because military specifications require lowers to be forged from aluminum rather than extruded from a billet.
Forged lower receivers are typically made from a block of 7075-T6 aluminum which is then heated and forced into a mold. After it has been hammered into shape, the final work of cutting dimensions and finishing is completed via machining.
The forging process creates an even distribution of aluminum molecules throughout the alloy matrix, which makes forged lowers somewhat stronger than billet lowers. Interestingly enough, they also tend to be a little bit lighter as well.
However, although forged receivers are stronger and sometimes lighter, they sometimes manifest imperfections which create a less than perfect match between the upper and lower receiver. In addition, some people don’t like the fact that there really aren’t any customizable forged lowers.
What Are Billet Lowers?
Billet lowers are typically made from 6061-T6 aluminum although they can also be made from the same 7075-T6 aluminum as well.
Instead of being forged into shape, billet lowers are CNC-machined into shape, under extremely tight tolerances that are sometimes so precise that they are measured down to a millionth of an inch.
As a result, the finished appearance of a billet lower is often superior to that of a forged lower. Although they are technically not as strong as most forged lowers, billet lowers generally offer a much tighter, better fit to the upper receivers with which they are paired. Billet lowers are also typically slightly heavier than forged lowers.
Some users also like the fact that billet lowers not only look better, but are customizable, as well. Billet lowers are often available in a wide range of finishes and colors.
Is There Any Substantial Difference?
There are not a lot of serious differences between forged and billet lower receivers.
Forged lowers will be slightly lighter than billet lowers and won’t have as precise of a finish, but they will be stronger. However, for the purposes for which a rifle lower is used, this will probably never be noticed.
Billet lowers cost more and are more customizable than forged uppers, so there is a tradeoff there.
There is a more substantial difference between 6061-T6 and 7075-T6 than there is between forged and billet lowers. 7075-T6 is substantially stronger; but again, for what they are used for, it doesn’t make a huge difference.
In other words, you can make a perfectly serviceable rifle with either a forged or billet lower receiver and a parts kit. The choice is yours.
Where Can You Get a Lower Parts Kit to Complete Your Home Build
Looking for an AR-15 lower parts kit or a build kit that includes almost everything you need to complete a finished rifle at home?
MCS Gearup carries lower parts kits as well as piecemeal AR15 lower parts you need to build rifles, make repairs and upgrades, such as buffer tubes, castle nuts, pistol grips and takedown pins.
They also carry lower parts kits for Glock 17 pistols and other popular Glock pistols in addition to their AR parts. Among their polymer 80 lowers and lower parts kits for Glock 17 pistols and other models are a wide variety of piecemeal Glock lower parts.
Visit their website today to learn more or get in touch with them directly at 239-848-6757.
