Spring Compressor Question

[rr_shooter]

I'm making a spring compressor based upon some of the ideas I've seen on this site.  My question is, how much travel do you need to allow on the screw to back off the tension on the spring?  

I'm first going to take apart a new B3-1, but I also have a RWS 36 that I might want to disassemble someday.  I figure the length required may vary depending on the gun, so if you could give me a conservative estimate, it would be appreciated.

[preez]

The one I build uses 6" chopped off "c" clamp it travels roughly 3.5"-4" and it was plenty for my Gamos and a b26.

hope this helps

chris

[rr_shooter]

Thanks, Chris.  I was figuring about 4" would be sufficient, but I wanted to get some confirmation so I wouldn't build it too small.