KP2743-1-62S - Lincoln Magnum PRO 550A MIG Nozzle, 5/8 Bore, 1/8 Stickout, Thread-On

Technical Overview of the Lincoln KP2743-1-62S

The Lincoln Electric KP2743-1-62S is a premium gas nozzle engineered specifically for the Magnum® PRO 550A series of semi-automatic MIG welding guns. Designed to meet the rigorous demands of high-amperage industrial welding, this component is rated for 550A applications. It features a standard 5/8-inch (15.9 mm) inner diameter (ID) bore, which provides a balanced gas flow suitable for a wide range of transfer modes, including spray transfer and globular transfer, where adequate shielding coverage is critical to prevent porosity.

This specific nozzle configuration offers a 1/8-inch (3.2 mm) stickout relationship. The stickout dimension is defined by the recess of the contact tip relative to the nozzle face; in this case, the tip is recessed, allowing for a 1/8-inch electrode extension before the wire passes the nozzle plane. This geometry helps protect the contact tip from excessive radiant heat and spatter accumulation while maintaining sufficient electrical stickout (ESO) for stable arc characteristics. The nozzle utilizes a thread-on connection mechanism, which mates directly with Magnum® PRO 550A thread-on diffusers. Unlike slip-on variants, the threaded interface ensures positive mechanical retention and precise concentricity, reducing the risk of gas turbulence caused by misalignment.

Material construction is a key differentiator for the Magnum® PRO line. The KP2743-1-62S is nickel-plated, a surface treatment chosen for its superior resistance to spatter adhesion compared to bare copper or brass. This plating facilitates easier cleaning and extends the service life of the consumable by preventing the buildup of molten material that can obstruct gas flow. Additionally, the nozzle features coarse threads designed to withstand thermal expansion and contraction cycles without seizing, ensuring that maintenance personnel can remove and replace the unit efficiently even after prolonged use in high-heat environments.

Compatibility Note: This nozzle is strictly compatible with Magnum® PRO 550A guns equipped with 550A thread-on diffusers. It is not interchangeable with 350A series consumables or slip-on diffuser systems.