Selecting the Right Polymer 80 Billet
Choosing the ideal Polymer 80 billet is essential for ensuring a successful 80% lower build. Here are some crucial factors to consider when selecting the right billet:
Material Composition:
Polymer 80 billets are typically made from either nylon or reinforced polymer. Nylon billets are more flexible and prone to warping, while reinforced polymer billets offer increased rigidity and durability. Consider the intended use and desired performance characteristics when making your choice.
Design and Compatibility:
Various Polymer 80 billets are available in different designs and configurations. Some billets are compatible with specific firearm models, while others offer more versatility. Determine the type of firearm lower receiver you intend to build and choose a billet that matches its specifications.
Size and Dimensions:
Polymer 80 billets come in different sizes and dimensions. Ensure that the billet you select corresponds to the frame size of your chosen firearm. Accurate measurements will prevent compatibility issues and ensure a proper fit during assembly.
Manufacturer Reputation:
Choosing a billet from a reputable manufacturer is crucial. Reputable manufacturers employ high-quality materials, precise machining techniques, and rigorous quality control measures. This ensures the reliability, durability, and overall performance of the final product.
Warranty and Support:
Consider the warranty and support offered by the manufacturer. A comprehensive warranty provides peace of mind and protection against defects or manufacturing issues. Additionally, having access to technical support can be invaluable during the assembly process.
Required Tools and Equipment
To assemble a Polymer 80 BBS, you will need the following tools and equipment:
1. Safety Gear
- Safety glasses
- Hearing protection
- Gloves
- Dust mask
2. Gunsmithing Tools
- Polymer 80 BBS kit
- 80% lower receiver
- AR-15 upper receiver
- AR-15 barrel
- AR-15 bolt carrier group
- AR-15 charging handle
- AR-15 stock
- AR-15 pistol grip
- AR-15 handguard
- AR-15 muzzle device
- AR-15 magazine
3. Other Tools and Equipment
- Drill press
- Drill bits
- Tap and die set
- Hammer
- Punch
- Screwdrivers
- Wrenches
- Allen keys
- Lubricant
| Tool | Purpose |
|---|---|
| Drill press | Used to drill holes in the lower receiver for the trigger, safety, and other components. |
| Drill bits | Used to create holes of various sizes in the lower receiver. |
| Tap and die set | Used to create threads in holes in the lower receiver. |
| Hammer | Used to drive pins and roll pins into place. |
| Punch | Used to remove pins and roll pins from place. |
| Screwdrivers | Used to tighten and loosen screws. |
| Wrenches | Used to tighten and loosen nuts and bolts. |
| Allen keys | Used to tighten and loosen screws with hexagonal heads. |
| Lubricant | Used to lubricate moving parts to reduce friction and wear. |
Selecting and Installing the Upper Receiver
The upper receiver is one of the most important components of a Polymer 80 lower, as it houses the bolt carrier group, charging handle, and barrel. When selecting an upper receiver, you’ll need to consider the following factors:
- Caliber: The upper receiver must be compatible with the caliber of the barrel you plan to use.
- Length: The length of the upper receiver will determine the overall length of the rifle.
- Material: Upper receivers are typically made from aluminum or forged steel. Aluminum is lighter and more affordable, while forged steel is more durable.
- Features: Some upper receivers come with built-in features such as forward assist, dust cover, and brass deflector.
Installing the Upper Receiver
To install the upper receiver, follow these steps:
1.
Remove the dust cover from the upper receiver.
2.
Align the rear pin hole of the upper receiver with the takedown pin hole of the lower receiver.
3.
Insert the takedown pin and push it into place.
4.
Close the dust cover.
5.
Insert the charging handle into the upper receiver and pull it back to engage the bolt.
6.
Check the fit and function of the upper receiver by inserting and removing a magazine, charging the bolt, and dry firing the rifle. The upper receiver should mate securely with the lower receiver, and all controls should operate smoothly. If you encounter any problems, refer to the manufacturer’s instructions or consult with a gunsmith.
Gas System Configuration
Buffer Tube & Buffer Spring
Choose a buffer tube compatible with your lower receiver. Common lengths are carbine, mid-length, and rifle-length. The buffer spring should correspond to the length of the gas system.
Buffer Weight
The buffer weight dampens recoil. Heavier weights reduce felt recoil but may delay cycling. Standard carbine buffer weights (3 oz) work well for most gas systems.
Gas Block
The gas block channels gas from the barrel to the gas tube. It must align precisely with the gas port on the barrel. Gas blocks come in different heights, so choose one that matches the diameter of your barrel.
Gas Tube
The gas tube connects the gas block to the gas key on the bolt carrier. Ensure it is the correct length for your gas system. Common lengths are carbine (7″), mid-length (12.5″), and rifle-length (16″).
Gas Key
The gas key is a mechanism on the bolt carrier that interacts with the gas tube to cycle the action.
Gas Port Size
The diameter of the gas port on the barrel determines the amount of gas that reaches the gas system. Smaller ports require higher pressures to cycle the action.
Gas System Length
The length of the gas system refers to the distance between the gas port and the gas key. It influences the dwell time (the amount of time the bolt remains open) and the recoil impulse.
| Gas System Length | Advantages | Disadvantages |
|---|---|---|
| Carbine (7″) | Compact Lightweight |
Higher recoil Lower reliability with underpowered ammunition |
| Mid-length (12.5″) | Increased dwell time Reduced recoil |
Longer than carbine May require adjustable gas block for reliability |
| Rifle-length (16″) | Longest dwell time Lowest recoil |
Bulky May require heavy buffer weight for reliability |
Final Assembly and Function Check
Loading the Magazine
Insert a loaded magazine into the magazine well. Make sure the magazine is securely seated.
Racking the Slide
Grasp the charging handle and pull it towards the rear to fully rack the slide. This will chamber a round.
Safety Check
Verify that the safety is in the “safe” position.
Trigger Check
Place your finger inside the trigger guard and check the trigger travel. It should move smoothly without any hesitation.
Sight Alignment
Align the sights as desired. Check that the front sight is level with the rear sight.
Pushing the Magazine Release Button
Depress the magazine release button on the side of the pistol. The magazine should drop free.
Releasing the Slide
Slowly release the charging handle to allow the slide to go forward. This will unchamber the round and return the pistol to battery.
Trigger Removal
Remove your finger from the trigger after firing.
Ejection Port Observation
Observe the ejection port to ensure that the spent casing has been ejected properly.
Safety Closure
Once the function check is complete, engage the safety to prevent accidental discharge.
Cleaning and Maintenance
After firing, clean and maintain the pistol as per the manufacturer’s instructions. Regular cleaning will ensure optimal performance and extend its lifespan.
How To Put Together A Polymer 80 Bbs
Putting together a Polymer 80 bbs is a relatively simple process, but it does require some basic tools and knowledge. Here’s a step-by-step guide on how to do it:
- Gather your tools and materials. You will need:
- A Polymer 80 bbs
- A drill press
- A 3/16-inch drill bit
- A 1/4-inch drill bit
- A 5/16-inch drill bit
- A 1/2-inch drill bit
- A 9/16-inch drill bit
- A 5/16-inch x 18-thread tap
- A 1/4-inch x 28-thread tap
- A 5/16-inch x 18-thread die
- A 1/4-inch x 28-thread die
- A 3/16-inch hex wrench
- A 1/4-inch hex wrench
- A 5/16-inch hex wrench
- A 1/2-inch hex wrench
- A 9/16-inch hex wrench
- A hammer
- A punch
- A vise
- Prepare the Polymer 80 bbs. This involves removing the trigger housing and magazine release.
- Drill the holes in the Polymer 80 bbs. The holes need to be drilled in the following order:
- Trigger pin hole (3/16-inch)
- Hammer pin hole (1/4-inch)
- Sear pin hole (5/16-inch)
- Disconnector pin hole (1/2-inch)
- Extractor pin hole (9/16-inch)
- Tap the holes in the Polymer 80 bbs. The holes need to be tapped in the following order:
- Trigger pin hole (5/16-inch x 18-thread)
- Hammer pin hole (1/4-inch x 28-thread)
- Sear pin hole (5/16-inch x 18-thread)
- Disconnector pin hole (1/2-inch x 13-thread)
- Extractor pin hole (9/16-inch x 18-thread)
- Install the parts in the Polymer 80 bbs. The parts need to be installed in the following order:
- Trigger
- Hammer
- Sear
- Disconnector
- Extractor
- Trigger housing
- Magazine release
- Test the Polymer 80 bbs. Make sure that the trigger, hammer, and sear are all functioning properly.
People Also Ask About How To Put Together A Polymer 80 Bbs
How difficult is it to assemble a Polymer 80 Bbs?
Assembling a Polymer 80 Bbs is not difficult, but it does require some basic tools and knowledge. If you have never assembled a firearm before, it is recommended that you seek the assistance of a qualified gunsmith.
What are the benefits of assembling a Polymer 80 Bbs?
There are several benefits to assembling a Polymer 80 Bbs, including:
- Customizability: You can customize your Polymer 80 Bbs to meet your specific needs.
- Cost savings: Assembling a Polymer 80 Bbs can save you money compared to buying a complete firearm.
- Learning experience: Assembling a Polymer 80 Bbs can be a great way to learn about how firearms work.
What are the risks of assembling a Polymer 80 Bbs?
There are some risks associated with assembling a Polymer 80 Bbs, including:
- Improper assembly: If the Polymer 80 Bbs is not assembled properly, it could malfunction or even be dangerous to use.
- Legal issues: In some jurisdictions, it is illegal to assemble a Polymer 80 Bbs without a license. It is important to check your local laws before assembling a Polymer 80 Bbs.
