Checked out a Gen 4 G26 yesterday and was able to compare it to a Gen 3. The 4 felt slightly better in my hand but I'm not sure I can easily CC a double stack. Is there anything else different between the Gen 4 G26 and the Gen 3 besides the grip and the mag release? Any other mechanical differences (ex. different guide rod/spring assembly)? I've been reading about the issues some have had with the G19s re: the guide rod/spring. Are the rest of the parts the same as Gen 3s? When did the 4s start rolling off the assembly line? Thanks.