I'm planning on making a jig to determine the tension ( pound weight ) on FWB 300 springs.
I want to compare the difference between new springs, old springs, old springs and new springs, difference between double springs and a single spring and also how much of a difference, ( if any ) if I leave the spring loaded overnight, like leaving the gun cocked.
To make the jig isn't a big deal, what is important is having an exact measurements of how much the spring is compressed before it's cocked and the distance after it's cocked.
Although not the only factor, I'm interested in knowing how close new springs are to each other. I'm curious to know if this can be one of the reasons Chrony number vary when replacing new springs even on the same gun.
Does anyone know this compressed measurement on the FWB 300 springers ? Thank guys.
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.