The Lantac UFA-S Ultimate Forward Assist (Solid) from Lantac is precision engineered to deliver enhanced strength, corrosion resistance, and reliability for demanding rifle builds, featuring Swiss lathe turned 4140 Cr-Mo steel that surpasses original materials in durability. All components are heat treated to 48-52 Rc and then QPQ Nitrided to further boost corrosion resistance and lifespan, while the main plunger spring uses Stainless 316 music wire (ASTM A313) for superior corrosion resistance and fatigue performance. Closed end coils replace open ends to improve seating and alignment, with springs stress relieved and air cooled to maintain consistent performance under heat and pressure. The plunger detent spring is constructed from Zinc plated music wire (ASTM A288) for added corrosion resistance, and all springs receive mil-spec stress relief to ensure long-term stability. An improved spiral design pin retains the assembly within the upper receiver, delivering increased strength and durability compared with slotted alternatives. The Cap design has been streamlined by reducing diameter and removing snag points, while exterior knurling around the edge facilitates positive engagement with gloved or bare hands, and the overall weight drops to 20.227 g (0.7135 oz) from 22.481 g (0.7930 oz). All outer details are bead blasted to a satin, low-reflectivity finish, and the parts are proudly manufactured in the USA from USA-sourced materials and finishes.