Clay target thrower spring

[Guest seawolf138]

I found a old thrower in the garage while cleaning up.  No one in the family knew we had one, something my grandfather bought probably 30+ years ago, and I was interested in getting it fixed.  I went to Home Depot and got a 6" 34lb spring, and it is nowhere near strong enough and it seems to be a little short.  I'm thinking I need a 7.5" spring, but I'm not sure how much heavier I should make it.  Any suggestions?

 

The trap that I found is pretty much identical to this one 

 

http://www.academy.com/webapp/wcs/stores/servlet/Product_10151_10051_33539_-1__?N=85400437

 

Sorry for the stock picture instead of an uploaded photo, but I loaned my cell phone to my sister for the afternoon and can't get a picture of it at the moment.

 

Thanks in advance for any advice/help

[Westwindmike]

Those are really strong springs. Maybe look at garage door springs? Or write the manufacturer?

[RED333]

Try this

http://www.qualityreplacementparts.com/