10401129 - Tweco Classic No. 4 MIG Gun 400A 25ft Miller Backend

Technical Precision: Tweco 400 Amp Air-Cooled MIG Gun

The Tweco® 1040-1129 Professional Classic® No. 4 MIG Gun is a high-performance, 400-amp air-cooled torch designed for the rigorous demands of industrial welding. Rated at a 60% duty cycle with CO2 gas, this gun is built to deliver consistent results in semi-automatic welding applications. It comes factory-ready for wire sizes ranging from .035" to .045", making it versatile for a wide array of solid and flux-cored wire applications. The rear connection is a direct plug Miller® style, ensuring a secure and conductive fit with compatible power sources.

At the core of this gun's performance is the 3-layered conductor tube construction, consisting of a copper tube, silicon-resin glass insulator, and a metal jacket. This design ensures maximum electrical conductivity while maintaining thermal insulation and physical durability. The conductor tube is angled at 60 degrees and can swivel a full 360 degrees around the handle, allowing the operator to access hard-to-reach joints without straining their wrist or the cable. The connection at the wire feeder is the fully insulated MIG-Kwik system, which promotes safety and speed when setting up or breaking down equipment.

Wire feedability is critical in MIG welding, and the Tweco Classic No. 4 excels in this area. The 25-foot cable assembly is supported by a robust steel spring strain relief at the handle, preventing kinking and ensuring smooth wire delivery. Two ball-point screws secure the Cablehoz® and conductor tube within the handle, creating a solid mechanical connection that resists loosening under vibration. With its heavy-duty contact tips and high-heat capability, this gun is an essential tool for welders seeking precision and reliability.

Specifications and Features

• Amperage Rating: 400 Amps @ 60% Duty Cycle (CO2).
• Cooling: Air-cooled design for simplicity and portability.
• Connector: Miller® style rear plug for direct connection.
• Ergonomics: Balanced oval handle with bottom gun hanger for easy resting.
• Repairability: Easy-to-service design with interchangeable parts across the Tweco Professional series.