So I am currently building a couple SBR's with left over parts. I was short a few items so I ordered the parts that I could from LaRue. I had to get a buffer tube and spring for a CTR stock and I went ahead and ordered a complete RAT stock with tube, spring, and castle nut.
As I was examining the brown box, I noticed the spring that came with the tube and RAT stock was 2" shorter than the "heavy duty spring" I got with the other tube for my CTR stock.
Is there any reason why these spring are in such difference? Is the RAT stock spring not a heavy duty spring? Will the 2" make a noticeable difference in certain platforms? These SBR's will be shot in SEMI mode (mostly, unless I drop an RDIAS in it). Lastly, which one should I install on which gun (300 BO, 5.56, and 9MM)?