The Stainless Steel Precision Inner Barrel 6.03 mm (PIB310) from FPS is a precision upgrade inner barrel designed for electric airsoft rifles (AEG), focused on improving shot consistency, air efficiency, and overall accuracy.

It is manufactured in Italy from a precision-drawn stainless steel tube (AISI 304), which undergoes multiple machining and finishing processes including CNC machining, internal reaming, lapping, and ultrasonic polishing. This results in a very smooth internal surface designed to reduce friction and improve BB stability during travel.

The barrel has a 6.03 mm internal diameter, which classifies it as a tightbore barrel. This tighter bore helps improve air compression behind the BB, contributing to more consistent velocity and improved grouping when paired with a properly tuned hop-up system and quality BBs.

With a 310 mm length, it is intended for standard AEG rifle setups using Tokyo Marui–compatible hop-up systems, making it suitable for a wide range of M4-style and similar platforms depending on internal configuration.

Stainless steel construction also provides high mechanical resistance and resistance to oxidation compared to brass or aluminum barrels, and allows easier cleaning of internal residue without damaging the surface.

Because of its tight tolerances, it performs best with high-quality BBs and a clean hop-up system, as debris or inconsistent ammunition can negatively affect performance.

Key Features

FPS PIB310 6.03 × 310mm AEG inner barrel
Made in Italy from AISI 304 stainless steel
Precision CNC-machined and polished internal surface
6.03 mm tightbore improves compression and shot consistency
Length of 310 mm suitable for standard AEG rifle platforms
Compatible with Tokyo Marui–spec hop-up systems
High resistance to wear and oxidation
Requires high quality BBs and regular maintenance

A precision stainless steel upgrade inner barrel designed to deliver improved consistency, stable compression, and enhanced accuracy in compatible AEG airsoft platforms.