Sold Item #C1686 German MP-40 Recoil Spring Unit Maker: German Model: M&P Caliber/Gauge: Description: Original German MP-40 recoil spring unit. Complete and original. Select Related Products: "German" "M&P" To see our other related products, select any combination of Maker, Model or Caliber above. By clicking on a check box you will add or remove a parameter for related product suggestions.