Whether you’re interested in building your first or your fifth AR, there should be lots of questions floating around.
Do you want to build from a kit or get the parts piecemeal? What caliber do you want to build? What sort of gas system do you want? What muzzle device, handguard and rail system, and what finish on the BCG?
These are just a few of them, but we’re here to tackle some of the questions associated with AR parts. Let’s start with AR-15 lower parts kits and what they come with.
What Comes with an AR-15 Lower Parts Kit?
Assuming what you are looking at is a complete AR-15 lower parts kit, it should come with:
- A pistol grip and hardware to secure it
- A safety selector lever
- The safety detent and spring
- A trigger
- Trigger spring
- Trigger guard
- A hammer
- Hammer spring
- Hammer pin
- Takedown and pivot pins
- Bolt catch spring, roll pin and plunger
- Disconnector and spring
- Detent plunger and retainer spring
- Disconnector and spring
- Mag catch assembly
- Mag catch button and spring
Other AR-15 lower parts kits may be slightly different, but as a general rule, a complete lower parts kit should come with all of the parts mentioned above.
What Comes with an Assembled Upper?
To complete a fully functioning rifle, you will also need an upper to mate to the lower (along with the lower receiver itself, more on that in a moment).
One option is to buy an assembled upper, which is also known as a complete upper and contains all of the upper parts needed to assemble a functioning rifle. In general, assembled uppers come with:
- The stripped upper itself
- A bolt carrier group
- A barrel, hardware, and muzzle device
- A handguard
- A gas system
- An ejection port cover
- A charging handle
- A forward assist
A true complete upper will have everything you need to pair it with a complete lower and so to complete a functioning rifle.
If I Build with a Stripped Upper, What Will I Need?
One alternative avenue for building an AR-15 rifle with an assembled upper is to buy a stripped upper, then get all of the other parts you will need, piecemeal.
This includes, as mentioned above, the upper itself, along with a barrel, muzzle device, gas system, handguard, ejection port cover, charging handle, and forward assist.
You will also need a bolt carrier group (not all assembled uppers come with them), along with a magazine and a buffer system, even though these are not expressly AR upper parts.
Do I Need an FFL Transfer for an Upper?
The ATF does not regulate the upper, or an assembled upper, as a firearm, even though it is needed to complete a finished and functioning rifle. Therefore you can buy an upper, or even an assembled upper, as though it were any other firearm part, without an FFL transfer.
Do You Need One for an AR-15 Lower Parts Kit?
The same considerations apply for AR-15 lower parts kits. Since they do not contain the lower receiver itself, you will not need an FFL transfer to buy one.
What Is a Lower Blank?
A lower blank, also known as a receiver blank, 80% lower, or pejoratively as a “ghost gun” is a receiver that has not had the recesses for the fire control unit or trigger group/pins machined out, and so cannot be used to assemble a finished rifle.
Many states and other local jurisdictions have outlawed purchase, transfer or possession of 80% lowers. If you are considering a project that involves one, be sure to consult a knowledgeable firearms lawyer in your area before doing so.
Do I Need an FFL Transfer for a Lower?
The lower receiver is the component that the ATF regulates and considers the “gun” itself, and therefore, an FFL transfer including a NICS check is required to buy one, just as if you bought a complete firearm.
A complete AR build kit may contain everything you need to assemble a finished rifle minus the lower receiver itself.
Build or Buy?
If you are on this page, one of the questions you will have to ask yourself is whether you’d rather build a rifle from scratch or just buy a finished rifle.
That’s up to you. Buying a complete rifle is easier and faster, and better for those without a solid working knowledge of firearm mechanics.
At the same time, building a rifle will give you the flexibility to customize the build as you go, so for some users, that is the preferred avenue.
Really, it all comes down to what your goals are for the project, and what you are looking for in a finished rifle.
Explore AR Parts, Kits and More Here
Here for an AR-15 lower kit, an assembled upper, or some other AR parts? Shop our full collections via the previous links and get in touch with us at Sales@MCSGearup.com if you have any questions.