The G30S comes with the SF frame, which is 2mm shorter front-to-back, than the standard G30 frame.
The G30 Gen 4, naked, comes with what Glock claims to be an SF-sized frame, and +2mm and +4mm backstraps. Glock probably knows better than I, but the Gen 4 30 frame feels just a hair smaller than the SF frames.
But for all practical purposes, G30S has the SF frame which is the same as the naked Gen 4 frame.
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