The Gorilla Machining Stainless Steel Guide Rod Assembly is a perfect match for a complete drop-in unit made from solid one piece of stainless steel. This will eliminate guide rod flex and ensure it will not chip, crack or break like other plastic guide rods in this industry. providing a lifetime of reliable service. Flat wound recoil springs are the best for optimized performance and are manufactured of certified aerospace spec materials, heat treated, and stress relieved to maximize durability. The screw tip is easily removed to allow the user to replace the spring weights and super fine tune the recoil spring to any ammunition towards the gun industry of choice.