Finding the right mid-length gas tube size is crucial for optimal functionality and reliability of your AR-15 platform rifle. This guide will delve into the specifics of mid-length gas systems, the importance of proper sizing, and how to choose the correct tube for your build. We'll also explore common issues and troubleshooting tips to ensure your rifle runs smoothly.
Understanding Mid-Length Gas Systems
The gas system in an AR-15 regulates the amount of propellant gas diverted from the barrel to cycle the action. A mid-length gas system strikes a balance between the shorter carbine and longer rifle-length systems. The gas port location on the barrel sits approximately halfway between the carbine and rifle lengths. This results in a gas tube that’s longer than a carbine system but shorter than a rifle system. The key advantage is a good balance of reliability, reduced recoil, and less wear on the operating components.
Advantages of Mid-Length Gas Systems:
- Reduced Recoil: Compared to carbine-length systems, mid-length systems typically exhibit less felt recoil. This is because the longer gas tube allows for more controlled gas pressure.
- Improved Reliability: Mid-length systems tend to be more reliable than carbine systems, especially with suppressed barrels or heavier loads. This is attributable to the less intense gas impulse.
- Less Wear and Tear: The moderated gas impulse translates to less stress on the bolt carrier group and other moving parts, extending the lifespan of your rifle.
- Balance between Reliability and Recoil: Mid-length gas systems provide a sweet spot between the reliability of a rifle-length system and the manageable recoil of a carbine-length system.
Disadvantages of Mid-Length Gas Systems:
- Slightly Increased Length: The longer gas tube adds a small amount of overall length to the rifle.
- May Require Specific Gas Blocks: The gas block's location on the barrel necessitates a certain type of gas block, possibly different from what a carbine or rifle system would use.
Choosing the Correct Mid-Length Gas Tube Size
The most common mid-length gas tube size is 0.220" (5.59mm) inner diameter, matching the common size of the gas port in barrels designed for mid-length systems. It's extremely important to match the gas tube's internal diameter to your barrel's gas port diameter. Using the incorrect size can lead to malfunctioning. A tube too small will cause failures to cycle, while a tube too large will result in excessive gas pressure and potential damage.
Identifying Your Barrel's Gas Port Size:
You can find the gas port size on the barrel's specifications or directly measure it, though this requires precision tools. Always double-check the gas port size before purchasing a new gas tube.
Installation and Troubleshooting
Installing a mid-length gas tube requires some familiarity with AR-15 assembly. Consult a reputable AR-15 assembly guide or seek assistance from a qualified gunsmith if you're unfamiliar with the process. Incorrect installation can lead to malfunctions or damage.
Common Issues and Troubleshooting:
- Failure to Cycle: This is often caused by an improperly sized gas tube, a blocked gas port, or an issue with the gas block. Check the gas tube and gas port for obstructions. A smaller-than-needed gas tube may be the cause.
- Excessive Gas Pressure: Excessive gas pressure can indicate a too-large gas tube or improper gas block installation. This can lead to damage to components or excessive wear.
- Gas Leaks: Leaks around the gas tube or gas block connections can be addressed by tightening connections or replacing worn-out parts.
Conclusion
Selecting the correct mid-length gas tube size is vital for the reliable operation of your AR-15. Choosing the right size gas tube – typically 0.220" inner diameter – and ensuring correct installation are key to avoiding malfunctions. Understanding the advantages and disadvantages of a mid-length gas system will help you choose the best option for your build. Always prioritize safety and consult a qualified gunsmith if you encounter issues. Remember that this information is for educational purposes, and handling firearms requires proper training and adherence to all safety regulations.