Originally Posted by intenseneal
They all feed just fine.
Then there's no problem to "fix".
Seriously, there was a mag body design revision which prevents older followers being used in newer mag bodies, and they've continued to make revisions to help improve feeding of assorted hollowpoints even in the newer mags.
A current listing of Glock Parts explains which followers can be used in which production vintage of mag bodies, if someone is really interested. Not hard to find online.
A few years ago I was experiencing some feeding stoppages with then-new G27 mags that came with the #6 .40 follower. When I discussed it with Glock (as an armorer), I was told that it might be due to a slight out-of-spec issue with the mag lips (liner), and that they'd inspect and replace the mags, but they agreed to send me the current .40 follower, first, which was the #8 version. (The #7 .40 follower didn't seem to be around that long.) The #8 .40 follower resolved my feeding issues and I kept the existing mags.
They've since come out with yet another one, the #9 .40 follower (which I've seen in even newer G27 mags), but I won't replace the #8's unless they either exhibit the "need' for it, or it comes time to replace them due to wear & tear (the G27 has more than 13+K rounds fired through it, and I mostly rotate through all my G27 mags over the year for range quals, training & practice
I still have much older G27 & G26 mags that are still in use and reliable with the assortment of differently numbered original followers, so I just replace mag springs periodically and leave the followers alone.
If they work, they work.