That is a Gen2 mate and one of my favourites. Gen1 had that fine stippling all the way around (I got my first Glock, a Gen1 in 87 or so before that serial numbered the frame for the US market). I have NO idea how many 10s of thousands of round went through it with bugger all cleaning !!!! When Glocks were adopted here in the mid 90s one of our recently trained armourers wanted to see my old one and offered to give it a once over, he was a bit astonished about the crud living inside it But it was still working just fine.