benefit to the anti rotation trigger pins?

It's my understanding that they cut down on wear to the lower receiver. Like if you look for new pins, there's actually 3 different sizes. The colt (large pin), standard .154, and then .155. The .155 is for receivers that have been worn over time by the pins.
 
Most people have them because they thing they look cool. The idea is the stop pins from moving around and over time wearing the holes in the receiver bigger, which could cause the pins to back out. I don't worry about that much, and use Geissele triggers in all my AR's and they caution against the KNS pins.
 
I see them on a lot of ar's now, like pof. What do they do that my regular
pins dont do or are they just cool looking?
Thanks,
Sean
A common reason why you see them in POF's is because some of them come with a drop in trigger that requires secured pins as the pins aren't secured by the springs as they are in a standard trigger group.
 
After installing a set on a factory Noveske N4 trigger (because I found them on sale locally and figured they couldn't hurt anything) I have found that they actually take some creep out of the pull. I will eventually put them in my guns that do not have Geisselle's in them.
 
From browsing posts by several SMEs on m4carbine, they conclude that the trigger pins should be lubricated and should rotate to some degree and that KNS pins cause more problems than they solve.

I've fired thousands upon thousands of round through ARs with GI triggers and never had a malfunction due to a pin walking out. I've shot a few thousand with SSA-equipped ARs and never had an issue with that trigger.

I would advise doing some research on AR-specific pages and look at what armorers and SMEs have to say. I believe there are a few forums where you could post the question to Larry Vickers, Rogers, etc.
 
If you have a receiver that for whatever reason the pins walk out of, which I've seen, they are considerably less money than replacing said receiver and fix it as long as everything remains close enough to proper geometry. They can moderately improve the feel of a trigger as they are machined much nicer than mil-spec pins. They look different without being gawdy. I don't run them, and the first thing I mentioned is the only reason I would. Like most things don't like them, don't buy them, if you have a need/want you know, don't believe marketing.
 
I was shooting a match with a GAP built DPMS LR308 that had a pin walk out on it. I was sure glad I discovered it between stages and was able to push the pin back without it affecting anything. Ordered KNS kits for all my rifles as soon as I got home.
 
Most people have them because they thing they look cool. The idea is the stop pins from moving around and over time wearing the holes in the receiver bigger, which could cause the pins to back out. I don't worry about that much, and use Geissele triggers in all my AR's and they caution against the KNS pins.

+1 like everyone else said I run all Geissele triggers in all my AR's and they said to stay away from these.