AEG Air Nozzle Length Chart – Choosing the Correct Nozzle

The air nozzle is a small component, but it has a major effect on feeding, air seal and muzzle-energy consistency in an AEG airsoft gun. The nozzle moves backwards and forwards during every shot. As it retracts, it opens the feed path for a BB to enter the hop-up chamber. As it moves forwards, it pushes the BB through the hop-up bucking lips into the firing position, seals against the bucking and directs compressed air behind the BB.

The gun model alone is not always enough to identify the correct nozzle. M4-series AEGs, for example, use several different nozzle lengths even when the guns look almost identical externally. The manufacturer, model revision, hop-up unit, cylinder head and tappet plate may all affect the required length and tip profile.

The AEG air nozzle chart at the end of this article contains 199 manufacturer- and model-specific entries. The dimensions are reference values rather than guaranteed compatibility specifications. Always measure the original nozzle before ordering a replacement and test the new nozzle in the exact build.

Updated 10 July 2026. Historical measurements in the chart should not be interpreted as a manufacturer compatibility guarantee.

What does an AEG air nozzle do?

The sector gear operates the tappet plate, which briefly pulls the nozzle backwards. With the nozzle retracted, a BB can rise from the magazine feed path into the hop-up chamber.

The tappet-plate spring then returns the nozzle forwards. The nozzle pushes the BB through the hop-up bucking lips into the firing position and presses against the rear of the bucking. When the piston moves forwards, compressed air travels through the cylinder-head tube and nozzle to the rear of the BB.

The nozzle must therefore perform three functions correctly:

• provide enough time and clearance for the BB to enter the hop-up chamber;
• push the BB into the correct firing position; and
• form the best possible seal between the cylinder head and hop-up bucking.

Why is nozzle length important?

In some builds, a difference of only a few tenths of a millimetre can affect feeding or air seal. The effect depends on the complete geometry of the gearbox and hop-up assembly.

A nozzle that is too short

A nozzle that is too short may not press firmly enough against the hop-up bucking lips. Possible symptoms include:

• air leakage;
• low or inconsistent muzzle energy;
• an unusual firing sound; or
• double feeding in some configurations.

A nozzle that is too long

A nozzle that is too long may remain too far forwards and fail to open the feed path sufficiently. Possible symptoms include:

• failure to feed;
• intermittent feeding;
• damaged BBs;
• folded or damaged bucking lips; or
• excessive friction between the nozzle and hop-up unit.

How to choose the correct nozzle

1. Measure the original nozzle

Use calipers to measure the original nozzle from its flat rear face to the furthest point of the tip. Calipers with 0.01 mm resolution are recommended.

Take more than one measurement because the tip may be angled and moulding marks can affect the reading. When the original nozzle feeds and seals correctly, its length is the safest starting point for selecting a replacement.

2. Check the tip profile

Nozzles with the same overall length may have different tip profiles. A tip may be flat, rounded, tapered or angled. The profile affects how the nozzle pushes the BB into the bucking and how it rests against the bucking lips.

Change the tip profile only when you know that the replacement is compatible with the hop-up unit and bucking in the build.

3. Choose standard or bore-up correctly

A standard AEG nozzle and a bore-up nozzle are not directly interchangeable. A bore-up nozzle is designed for the larger outlet tube of a bore-up cylinder head.

The original article lists an approximate internal diameter of 5.4 mm for standard nozzles and 5.7 mm for bore-up nozzles when measured at the rear. Dimensions vary by manufacturer, so internal diameter should not be used as the only selection criterion.

4. Check compatibility with the cylinder head

The nozzle must move freely around the cylinder-head outlet tube without excessive side play. A fit that is too tight can slow the tappet plate, while an excessively loose fit may reduce air seal.

When mixing components from different manufacturers, check at least:

• the nozzle's internal diameter;
• the outside diameter of the cylinder-head outlet tube;
• free nozzle movement across its complete travel;
• compatibility with the tappet-plate slot; and
• alignment with the hop-up chamber in the forward position.

5. Check the O-ring and lubrication

An O-ring nozzle seals around the cylinder-head outlet tube. One correctly sized O-ring is normally sufficient to produce a good seal.

A two-O-ring nozzle can be supported more steadily on the outlet tube and may reduce nozzle movement. It also creates more friction, so the nozzle, tappet plate and return spring must move especially freely. This is particularly important in high-speed builds.

Use only a small amount of lubricant suitable for the O-ring material. Excess lubricant attracts dirt and may migrate into the hop-up bucking.

6. Do not choose the material based on strength alone

AEG nozzles are manufactured from materials such as POM, polycarbonate and aluminium. When correctly aligned, all of these materials can perform well.

An aluminium nozzle resists mechanical wear, but it does not flex like a polymer nozzle. When the nozzle, hop-up chamber and inner barrel are not properly aligned, a hard metal nozzle may rub against the hop-up chamber or bucking lips. A polymer nozzle often tolerates minor alignment errors better.

Checking the nozzle after installation

After installing the new nozzle, check the complete assembly before regular use.

• Does the nozzle move freely by hand around the cylinder-head outlet tube?
• Does the tappet plate return fully forwards?
• Does the feed path open sufficiently when the nozzle is retracted?
• Does the nozzle push the BB through the bucking lips without damaging them?
• Does the nozzle seal against the bucking in the forward position?
• Does the gun feed in both semi-automatic and full-automatic fire?
• Is muzzle energy consistent when measured with a chronograph?

When the gun does not feed with the new nozzle, do not shorten the nozzle as the first response. Check tappet-plate movement, the nozzle slot, hop-up chamber position, magazine feeding and the condition of the bucking lips first.

How to use the AEG nozzle chart

Use your browser's find function to search the chart by manufacturer or model. On a computer, this is normally opened with Ctrl+F or Cmd+F.

In the chart:

• length means the overall length from the rear face to the tip;
• O-ring(s) shows the number of internal sealing rings;
• not verified means that a reliable value was not available; and
• a model entry may apply only to a specific manufacturer or product generation.

Important: The chart is a reference tool, not a compatibility guarantee. Manufacturers may change dimensions within a product line without making an obvious change to the gun's name. Always measure the original nozzle and test the replacement with the actual gearbox, cylinder head, tappet plate, hop-up unit and bucking.

AEG air nozzle lengths

Summary

The correct AEG air nozzle is selected using its tip profile, internal diameter, O-ring arrangement, tappet-plate interface and compatibility with the complete compression and hop-up assembly—not length alone.

The safest method is to measure a correctly functioning original nozzle and choose a replacement with the closest possible construction. The chart helps narrow down the options, but final compatibility must always be confirmed by installation, feeding tests and chronograph measurements.