Others have been skeptical for years as to why HK couldn’t fit 17 cartridges in the same size magazine that other manufacturers get 17 cartridges into.
I just bought some HK 17 rounders, and plan to try the spring and follower in a P2000 magazine. Seems like 15 should fit in there with a lot more margin than 15 in the mags for the 43X/48.