Replacement spring follower - Mec-Gar Plus1 Sig Sauer P226 Mags Basepad/Spring/Follower Conversion Kit

I ordered the replacement spring and follower for my Sig P226 15rd factory magazines. Replacement was easy but upon loading them was only able to load 14 rounds not 15 also the information that came with springs basically makes it sound like I would be able to add one more round, just the opposite it was minus one round