All the Glock production from Gen3 to Gen1 no longer has patent protection
Glock changes the design just a C hair and they get 20 years of patent protection
That is why all the P80 stuff is to Gen3 , they can't copy the Gen4 or Gen5 designs without patent infringement
Well, yes, mostly, but in a realistic sense it makes the most sense, as Gen3 is going to have the widest level of parts compatibility.
I think the biggest difference is the barrel, specifically its rifling.
But, here's a decent article: Glock 19 Gen 4 vs Gen 5 Comparison :: Guns.com
I just acquired a G43X, and I had my G43 (gen 4), on the bench at the same time. I noticed that the slide's slightly different, the front of it's "beveled" on the new gun, and the finish is different.View attachment 371087
Yes, although strictly speaking things like 42/43/43x/48 are sort of their own thing, but Glock is making subtle changes to a lot of guns, but there are subvariants within Gen5,
even. For example I have two 19 Gen5s, one has forward serrations on it, the other one doesn't. The one without FCS has the exaggerated magwell cut on the front.