I'm trying to find the correct recoil springs for both an original 4.25" M&P40 and a 2.0 5" M&P40. Many people keep saying they take the same springs and some even said the same guide rod. When I pull the guide rods from both and compare they are different. The 2.0 5" guide rod is a bit longer. Besides that there was about 32 coils on the original 4.25" and about 42 on the 2.0 5". I even emailed S&W but all I got was a quick "they have different parts numbers so they are different" reply. How could they take the same spring when I compare them and they are different? Where are all the 2.0 springs?