I have seen M16’s with egged pin holes. I will say these receivers had thousands upon thousands of rounds through them and were probably close to the end of their life expectancy. In any case, with the gov’t paying a couple hundred dollars or whatever it is for an M16 lower, it may just not make sense. For a Colt M16 in the NFR owned by an individual, that makes a difference because of the value of the receiver. They can be repaired, but who wants to go through that crap if you can avoid the problem all together. With the improvements with the Gen2 stuff, it may be a worthwhile investment. You have to consider though, will you ever shoot enough to realize the benefit?
I’ll bet the government gets their M16/M4 lowers for under $100
It makes sense to take preemptive measures with something as valuable as a transferable M16 lower.
I personally think the non-rotating pin is a beneficial improvement be it used on 9mm F/A or semi 5.56. The design is still evolving and I don’t think it’s fair to throw out the whole idea because of a few problems. I have them on my 5.56 and I admit, I like the way they look. I also like knowing that they will not ever walk out. If they break, so be it. Its only a BM lower anyway 
In all of my years I have yet to see “egged out” lower holes from pins. What I have seen are morons who have beat on them and pounded them in, incorrectly and other silly non sense.
I didn’t mean to imply the pin holes were grossly deformed, only slightly misshapen. I also didn’t meant to imply I 100% sure this was due soley to use. Could poor maintainance practices and/or ignorance be a contributing factor? Sure. I do know I have experienced pins walking a bit due to what I attributed to the out of round shape of the pin hole.
This is only slightly off the topic here, but has anyone ever removed the j-hook spring from the hammer when using KNS pins? It serves no purpose with these pins and removal would get rid of some friction. Without the groove for the spring to fit in, I would think there might be considerable tension exerted.
so let me get this straight, if I have a lower that has the hammer pin rotating as the trigger is pulled, these KNS pins are a “MUST” or not?
My dept has some hand me down guns (from the government) that are full auto and they have this rotating hammer pin issue, is this something that needs fixed or not?
It’s not something that really needs “fixed” Iraqgunz knows his stuff and if he hasn’t seen an “egged out” hole from rotating pins, I believe it.
It really comes down to if your dept. wants to spend $32 on each rifle. If the holes end up wearing, oversized pins are available.
No.
The only reason I’d buy the pins is if you’re running a 9mm AR and want a stronger hammer pin.
I think you might also consider what trigger you are using as most custom triggers come with their own pins. It is my understanding that the custom trigger’s pins are semi-proprietary in that you might be able to use the existing pins with them, but they will work work better with the supplied pins. Which means why reduce the function of say a Geissele SSA trigger by using KNS pins in it:(
Iraqigunz has seen more full auto ARs in every configuration imaginable than most of us will in a lifetime and if he has not seen an egged out pin hole, well, you be the judge
Must NOT.
Rotating pins is the engineered design.
Could you explain the rationale behind engineering that pin to rotate? I’m not a gunsmith, but I am a pretty good mechanic, and I can’t think of any reason for that pin to move. I’m surely missing something.
You’re not missing anything.
There’s no rotation engineered into the design.
I’m sure a small amount of rotation was accounted for in the design, but there is zero reason for those pins to rotate.
The spring captured pins are cheap to manufacture and easy to install, end of story.
Glock uses the same design pin as their trigger pin, but it’s the spring loaded slide stop lever that holds it in place.
If the pin does not move, then all of the stress and friction is put into a single point, in the center of the pin, which is its weakest point.
By allowing the pins to move, the center is not stressed as above; the friction point surface area is doubled and moved to the outside of the pins, where they are strongest.
Now in a low-rate-of-fire gun such as S/A, it might not matter much, but in a F/A gun friction is much much more severe.
ETA:
I do not mean rotate as 360 degrees round and round. I mean it rotates a little in conjunction with the hammer/trigger.
I’ve been using KNS pins for the last four years. I also use reduced power JP springs in my guns. In nine years of shooting ARs, I have seen two guns where one of the pins backed out causing the guns to stop working. With that thought, and the reduced power springs it gives me peace of mind knowing my pins won’t back out. Beyond that they are a gimmick. YMMV
I might add they were used hard in service and had parts replaced without doubt, so poor maintenance or parts replacement practices could always play a role. Remember, some of the few receivers I have seen that had this issue had been in inventory for decades with some having had little maintainance other than a cleaning. You are shooting a weapon and you notice the pin is walking a bit. You notice the pin hole is a bit misshapen. That is it. I mean they still shot, it was not like a catstrophic failure was neccsarily immanent. The fit of the pins was just a bit loose.
Not doubting he hasn’t experienced deformed or damaged pin holes that he could attribute to something other than someone beating the pins back in as he stated. It is unlikely in today’s world there are any decades old M16’s in inventory that have seen hard use in a combat environment as most are destroyed as unservicable, but perhaps a few slip through the cracks, and not seeing them doesn’t mean they haven’t existed.
So, to get back to the original question, are they necessary? No. Are they a bad idea? No. Do they work as advertised? Yes. Will most realize any benefit from them? Probably not. Would I run them on an NFA registered M16? Perhaps.
Wow, I’d like to see the engineering paper that describes that process with math. So, you’re saying that all the rotational force and friction of the hammer is concentrated on the groove in the center of the pin, unless that pin is allowed to rotate a few degrees. You inadvertantly just gave the perfect reason for the KNS design, which does away with the groove. Without that groove, the pin would be many times stronger and therefore should not have to rotate, which, of course, would obviate any chance of the holes in the receiver becoming worn because of said pin rotation. With the other advantage of not ever being able to walk out, they would seem to be a “no lose” product.
The only disadvantage I can see, is that it takes a little more time to completely strip the lower, but I can’t think of any scenario where I would be in a hurry to do that anyway.
Now, I’ve only witnessed, firsthand, one real world problem with an AR that the KNS pins would have prevented, but for a mere $30, I’ll keep using them in my guns, just in case.
We’ve got quite a few auto guns that are run real real hard.
We’ve experienced almost every kind of failure you can have, but NEVER a problem with walking pins or ‘egged’ holes.
EXACTLY.
Mouth breathers who are not authorized to be working on their guns, don’t have a clue, but think they do, are what causes lower holes to get “egged out” or “wallered out”.
If it is a work gun, go see your armorer.
Same applies for installing plates with single point attachments. I cannot tell you how many guys have approached me with issued M4s with a takedown pin spring that was mashed, half sticking out and said
“it was like that when I got it” .:rolleyes:
Actually you would be wrong as myself and many others who have been overseas have seen lowers that were originally M16A1’s that were restamped and in use by National Guard and Reserve units. To include Air National Guard personnel.
The most recent was around late 2006. Strangely enough the weapon was working fine and the holes had no issues.