https://pistol-forum.com/showthread.php?24159-Glock-19M/page51
Apparently the second pin was dropped to accommodate a longer recoil spring. No finger grooves, which people have been complaint about for almost two decades. Significantly redesigned internals that give a trigger break more similar to the new CZ. Traditional rifled barrel, which is purportedly giving noticiable improvements in accuracy. All steel sights instead of the plastic slide protectors that come on Glocks now. Even if Glock used the unsuspecting public as beta testers, as they did gen 4, I will probably buy a Gen 5 17 soon as they are available.
Apparently the second pin was dropped to accommodate a longer recoil spring. No finger grooves, which people have been complaint about for almost two decades. Significantly redesigned internals that give a trigger break more similar to the new CZ. Traditional rifled barrel, which is purportedly giving noticiable improvements in accuracy. All steel sights instead of the plastic slide protectors that come on Glocks now. Even if Glock used the unsuspecting public as beta testers, as they did gen 4, I will probably buy a Gen 5 17 soon as they are available.