Here is a comparsion of the Sig 238 recoil spring and the Mustang recoil spring which will work in the Sig.
The Mustang spring is on the top...notice that it's a double spring.
I had a problem with FTE with my Sig 238 and Sig is sending a new recoil spring. Here is a guy who they sent a new spring to....notice the size difference....
The new spring sent is on the bottom....he said he only had about 200 rds through the gun. I think they see that the orginal springs are a problem. The Mustang spring is a 12 #.
Going to be interested in which they send me.