An engineer at Suspa offered to make one custom for $105.00.......
Possibly helpful links:https://www.pyramydair.com/blog/2008/10/hw-55-tyrolean-part-5-how-to-measure-a-spring/https://www.customairseals.com/air-rifle-spring-cutting-procedure/
Apart from Hector Medina, contact Ron (Bayman) about spring material selection: https://www.gatewaytoairguns.org/GTA/index.php?action=profile;u=21540https://www.gatewaytoairguns.org/GTA/index.php?action=profile;u=33840
Ron,I think 72 lb cocked is rather low. I would expect perhaps triple that, depending on airgun power. What is the rated power of your Octane?If your rated power is 20 FPE, the energy in the cocked spring is typically 3 times that. 60 FPE stored over a 4" piston stroke would indicated 60 x 3 = 180 lb average force. So, depending on the spring rate, the force at full cock could be much more than 180 lb. For a gas spring, the force at the start and end of the stroke are much closer, than for the typical steel spring.
Music wire?Chrome vanadium?Chrome silicon?Valve spring wire?
Thanks for the invite Peter. This stuff is out of my wheel house. I'm not familiar with the gun and I can't say for sure but the avaliable stroke and spring length sound very long to me. I'm wondering if part of both those lengths was just space taken up by the ram body and not actually used stroke. That space perhaps could be taken up by a dummy plug and a more readily available shorter spring used. I'm just spit balling here. Without seeing the original guts of what were working with here I'm probably of little use. I do wonder if the gun itself is worth re-engineering it. That can only be determined by the owner.Be wellRon
Find out what the actual stroke is. Measure the end of the compression tube to the trigger latch. Then measure the piston from the face of the seal to the trigger latch receptacle. Subtract that piston length from the first measurement and that will tell you what the actual stroke is.You can't use the ram because afaik we don't know how much dead space it takes up with the ram body and any possible preload combined.Once you know your stroke length, you can shop for appropriate springs. You may not need a crazy long spring. Also does the trigger latch look compatible for a spring? Piston weight or lack of may come into play as well.