Walther Terrus spring

Group from new vortek spring
 
Thanks Ruben, mine is shooting 14.66 H&N FTT at 12.75 fpe. It's extremely accurate but I'm looking for it to reach out further without compromising accuracy. I don't know if you can obtain a thicker spring and if it would even increase fpe or how that would effect the dynamics inside the compression chamber. The search continues.
Thanks again
Gary