Can only fit 18 rounds into MecGar 22 round magazine with Toni Systems +4 base plate?

I picked up the 92xi brand new recently with 3 MecGar magazines with Toni systems +4 base plates. It was advertised at 22 round magazines, but I can only fit 18 rounds into the magazines. Tried with all 3 magazines it came with, and 18 rounds goes in fine but cannot force the 19th round in, let alone 22.

Is there some tip or trick to get 4 more rounds into these mags?