Combat Wrench MultiFunction Enhanced High Carbon Steel Spanner Hand Tool $ 22.90 Precision machined from carbon steel, through heat treatmnet, high hardness and durable in use. 22. This tool is used for castle nut removal and assembly, and it is also a standard length buffer tube wrench. 33. This tool can easily remove the old extension tube and mount a new style one without damaging the rifle finish. 44. With a rubberized grip for enhanced performance, safety and comfort. 55. Solid machined construction, high strength and light weight.