That's because the right spring in picture belongs to a #1Mk3 rifle magazine. When you look at them you see they're different. As stated your mag needs to be fitted when new and then stay with the rifle. They're mild steel and can be twisted so they misfeed. The one that pops rounds out needs lips reshaped. They should snap in cleanly or the spine needs to be altered a touch. Peter Laidlerspoke of having buckets of them salvaged and just sliver soldering a new locking spine on before fitting.