KNS pins actually "needed?"

[SouthPaw]

I was looking at some of my AR-15's last night and on my Seekins Billet lower I noticed the front trigger pins seems to be over hanging the receiver on the left side. I had to tap it back in so it was flush on both sides. I have noticed that my Noveske lower sometimes does this as well.

Both lowers are using different brands of parts kit (Noveske has PSA and Seekins has RGuns stainless). I know the KNS pins will probably "fix" the issue but will I just be putting a band-aid on something that is bigger? I researched it a bit and mostly have just come up "put some KNS pins on there and forget about it." I do like the way they look but AR-15 lowers have been going without them for how long now? Anyone have some insight?

[KS63]

Measure the pin holes in the receiver. I believe they should be .140". I'm tempted to say your receiver is within spec and your pin diameter is not. Others may have more to add. I measure everything on my receivers and parts before I assemble them in case there's a problem.

[ray1970]

Is the "front" pin the hammer pin? If so, I doubt that one could work its way out. It's usually held in place pretty tightly inside the hammer.

[kwando]

The pins should be grooved to prevent them from backing out. I don't think that they will ever fully blackout though, I could be wrong.

I like the look of them as well but when I added SSA triggers I removed them. Geissele does not recommend any anti-rotation triggers pins.

Is your hammer spring on top of the trigger pin? And how much of an overhang are we talking about?

[Hoser]

They are a cant hurt might help kind of a thing.

I have some on my rifles and some without.

[MarkCO]

If you have a cartridge type drop-in trigger, good chance they will move out to one side or the other. Some cartridge triggers, like the Jard Drop in, you don't even need the trigger or hammer pin, all they do is keep dust out.

But if you have a mil-spec style trigger, and the pins are walking out, there might be something slightly out of tolerance and in that case, the anti-walks will probably solve the problem.

[Circuits]

Ar standard hammer/trigger pins are .154". Colt oversize are .170".
KNS tight fit pins are .155", and also available in standard .154".

KNS pins are never necessary, but also never forbidden. If they make you happy, go buy them.

[O2HeN2]

I see three cases where they're a good idea:

Title 2 firearms (cheap insurance on an investment)
Completed 80% lowers (same reason as above)
Maybe prophylactically in a lower that you shoot the dickens out of


Otherwise wait and if you start seeing a problem develop, install them.

O2

[Mazin]

I use them on almost all of my builds after having 2 different rifles have the pins back out on me. For me it's worth the $30-$40.

[SouthPaw]

I decided to just order a set and put them on tonight. They look great and they should solve my problem. The hammer pin was the one giving me trouble. I don't think it would have ever actually backed out all the way but just dry firing it I could see it moving to the left. Plus since it's my SBR lower that I am waiting for my stamp it was cheap insurance. Thanks for your input guys!

[cofi]

Just remember that kns pins are a no go with geissele triggers