Ransom rests are great if you have a tight slide-to-frame fit, and that's really only for single stacks.
Glock's are very accurate, but you cant put them in a rest because they don't rely on a tight slide-to-frame fit. I've got a 9mm P-18 limited Para that shoots magnificently, but becuase it's stainless I could not tighten the slide to frame fit. Careful attention however was used when turning down the BBL, fitting the bushing, and fitting the lugs of the BBL and link pin, etc. It all locks up positively, but still cycles. Off a small rest, I can shoot quality 9mm in a ragged hole at 15 yards, around an inch or so at 25.