Nozzle size sets how much area the gas shield covers. A larger nozzle protects a wider pool, which suits high current and wide beads; a smaller one improves visibility and access into corners, at lower current.
Match it to the work: a 12 to 16 mm (0.47 to 0.63 in) bore covers most workshop MIG. Whatever the size, the nozzle must be clean — spatter build-up disturbs the gas flow and causes porosity that looks like a gas fault.
The questions welders ask
Should the nozzle be flush or recessed?
Most torches allow the contact tip to sit flush, slightly proud or recessed within the nozzle. Recessed gives better gas coverage and less visibility, and suits higher current; flush or slightly proud gives access and visibility for thin work. It is adjusted by which tip length you fit.
Last reviewed 2026-08-14