I want to have a new recoil spring on hand for my S&W 6906 in case they get hard to find. It is a used gun and I don't know the life left in the spring. I'm looking at the Wolff springs on Midway's site, but don't know which one to pick. The factory size is 15lbs isn't it? Should I stick with that, or go to something a little heavier. I plink/target shoot with FMJ whatever is on sale, but want to start keeping some JHPs in it for the nightstand. For what it's worth, the 16lb and 17lb spring is the only one that isn't a special order. On the other hand, the S&W spring is $1.99. Any advice is appreciated. Also, any opinions as to whether or not to invest in the front night sights?