Stock Compression Springs Catalog compression springs remove the hassle and difficulty in designing a part, Associated Spring RAYMOND has already done the work. Each spring is designed within proper stress levels and manufacturing limits. The term “spring steel” is a stock inventory term covering music wire, hard-drawn(MB) wire and oil-tempered wire. Additionally, stock compression spring materials may include stainless steel (300 series), beryllium copper, and phosphor bronze. Tolerances. Century Spring manufactures our stock springs to commercial tolerances, as defined by Century Spring Corp. (CSC) is North America’s leading catalog source of stock and custom springs for MRO and OEM applications for over 90 years. CSC features the largest stock spring selection in the world, as well as offering custom spring manufacturing services to fit your exacting quality standards.