I found a source for springs and found a size that is very close to the original recoil spring in my AKT 98. The original recoil spring has wire diameter of .035 and the outside diameter is close to .42". My original spring was close to 10" inches long before I clipped a few coils trying to improve functioning. The springs I found were 11" inches long and appear to have the same weight/newton strength as the original spring. I was able to order a 5 pack of these springs off the internet and got them in about 3 days. I bought the springs from mcmaster.com which is located in Elmhurst IL. McMaster-Carr is an industrial supplier but accepts small orders. The part number for the springs I ordered is 9637K75 and described as continuous-length compression spring, spring-tempered steel, 11" L, 42" OD, .035" wire packs of 5, Price $11.10, tax .89 shipping $5.50 total $17.49.
I tested one of these spring today and needed to shorten it to 10". After trimming to 10" rifle functioned better with SOG mags than my original spring that I may have cut to short. I tested the new spring uncut and I had a couple of doubles and once where the hammer didn't cock. I ended trying to shorten the spring in small increments and stopped at the 10" length. Considering I had been unable to find a suitable replacement recoil spring I am very pleased. I also have four more spare springs and I think the price was reasonable. I always liked having spare parts around for my guns and thought someone else might need a replacement.