d.b.d.2005. thanks for asking them same question I was going to ask... I have alloy frame 915 and after looking at the Wolff springs on Midway they say factory is 14lbs. and I was wondering too if maybe 16lbs might be a good idea.. but after reading this post i'll stock to 14lb.
my 915 looks like new so I am thinking not shot a lot but not knowing the age or round count on the recoil spring $8.00 is cheap to change and not hurt a guns frame.