OP - there is a reason why they are called "drop in triggers". Hell, Four Seasons advertises that they will install an Apex trigger that you purchase from them, while you wait. They have installed a couple of short reset triggers on my Sigs for me before I picked them up.
Chances are, if your buddy is ever in a place that an investigator is examining the type of trigger on his Glock, he has much much bigger problems than the stupid trigger. Like whether to accept the plea deal for manslaughter or go to trial for murder.
FWIW, the two main reasons I don't own Glocks are grip angle and the stock trigger. You can't really change the grip angle, but the trigger is an easy fix.
Finally, another NESer willing to call Glock stock triggers what they are- crap! Of course that goes hand in hand (ass?) for any striker fired pistol but we accept that.
Yes, they are called drop in for a reason. However, it is a firearm and some caution when modifying isn't such a bad thing. No reason to flame OP like this guy:
If your friend is too stupid to handle a punch then he is too stupid to handle a firearm.
You need a punch to replace a Glock trigger and about 5 min to watch a video on how to do it.
If you are a troll looking to stir up some shit about working on guns without a gunsmith license then gtfo.
If you were asking about welding rails into an AK receiver then it would be a different story, but the ease of the task makes your OP suspicious.
No need to be a dick. If you want to smoke out a troll, there are more artful ways to do it without being rude to a potentially sincere OP. Just my opinion. If he were to be enquiring how to weld rails to AK receiver- then it's time to be a dick for wanting to create such an abomination.