I just overhauled a 40 year old FWB 300S Match. I replaced the original spring with an OEM spring. I assume it was original because of the type and condition of the seals. After repair, there was no significant change in velocity. The OEM spring shown in the picture includes the spacer between the two springs. The new ARH spring shown is one piece from Macarri. After 40 years, the original spring didn't seem to change much. JSB 7.33 gr velocity increased from 639 to 649 fps. I expect the new spring will take some set after a while.