View Full Version : KNS Anti Rotation Pins....Is it a fluke or is there something technical behind it.
Obscenejesster
04-21-14, 09:14
I used KNS pins on my first build before I had any knowledge and before I knew they were unnecessary and serve no practical purpose. They are pretty much like throwing $30 down the drain. I never messed around with uninstalling them because they were the updated version with the stronger pins so I knew they wouldn't hurt anything. On this first build, I used an ALG QMS trigger for reference.
Fast forward to last week. I was working on my 3rd build and decided to use another ALG QMS since I was happy with the first. I used the stock pins that came with it and everything functioned completely fine. What I noticed was that it had a little bit of creep. Just a tiny bit but it was still noticeable. I wouldn't have thought anything about it except that the first QMS I installed had absolutely no creep whatsoever. I decided to remove it and install it again just for good measure. I got the same results.
I then began to think if the KNS pins had anything to do with it or if I just got really lucky with the first trigger. I wanted to find out so I decided to use my $30 Amazon credit on some KNS pins.
I got around to installing them last night and to my surprise, the creep went away. It felt exactly like my first ALG trigger.
So here's the question. Was this just a coincidence or is there something technical going on? I'm not the slightest bit versed in all of the technical aspects but does removing the slight amount of movement in the trigger pin remove a slight bit of creep?
Just for the record, the reason why I use the word slight is because I tried the KNS pins out with a Mil-Spec trigger that was included in a DD parts kit and I didn't notice any reduction in creep. I'm assuming it's because the trigger that came in the DD LPK had too much creep to start with.
I've found that for the most part, mild creep will go away as the parts settle in. KNS pins probably are helpful in niche circumstances, competition triggers, etc.
Creep attributed to the trigger pin's slight rotation?
Obscenejesster
04-21-14, 13:27
Creep attributed to the trigger pin's slight rotation?
I don't know....That's the only thing I can think of since the KNS pins wouldn't change anything else.
I don't know....That's the only thing I can think of since the KNS pins wouldn't change anything else.
They make different diameter pins. A thousandth or so could change the way the engagement surfaces interact.
Obscenejesster
04-21-14, 14:50
They make different diameter pins. A thousandth or so could change the way the engagement surfaces interact.
Cool....Makes sense. I suppose I will never know unless I buy some digital calipers.
Solution is to use the original pins.
Cool....Makes sense. I suppose I will never know unless I buy some digital calipers.
Obscenejesster
04-21-14, 15:19
Solution is to use the original pins.
Eh...I've already removed the trigger pins 5 times and don't feel like doing it again. I think I'll just keep the KNS pins in for now. They won't hurt anything and the trigger feels better with them.
The advantage of the KNS is that the side plates keep the pins in a fixed relationship; the pins cannot move away or towards each other as the trigger is pulled, while milspec pins can move towards each other just a bit as the trigger is pulled, adding just a bit to perceived creep. Don't think rotation has anything to do with this. While I had the same positive feeling about the trigger pull with my KNS pins as the OP, I ended up with the same creep free trigger pull by using Geissle's pins, which are slightly oversized compared to milspec, while made of harder steel and requiring no allen wrenches for disassembly, compared to KNS. Not sure if the ALG pins are the same as the ones sold with the Geissle trigger sets. If not, I would get a set of G pins.
The advantage of the KNS is that the side plates keep the pins in a fixed relationship; the pins cannot move away or towards each other as the trigger is pulled
This is at the sacrifice of the pins being allowed to roll in the lower. Without that, all the friction is forced onto the pin. Possibly a non-issue... but guys have made the argument over the years that if the pin fails, it can damage the lower pin hole.
Obscenejesster
04-22-14, 10:33
This is at the sacrifice of the pins being allowed to roll in the lower. Without that, all the friction is forced onto the pin. Possibly a non-issue... but guys have made the argument over the years that if the pin fails, it can damage the lower pin hole.
I never thought of that. So if a anti rotation pin fails, it will damage the lower possibly?
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I don't think the original style pins are likely to rotate in the receiver. The springs put a bit of pressure against the pins and there is a bit of natural sticktion when it's steel & aluminum. It only makes sense to size the pins & holes so the harder hammer & trigger rotate around the pin than to have the pin to rotate in the aluminum receiver and cause fretting.
The pins fretting in the receiver isn't a problem, otherwise we'd be complaining about all the threads concerning the use of steel bushings to repair worn pin holes
I don't think the original style pins are likely to rotate in the receiver.
I can go cock my hammer on most of my ARs now and watch the pin turn.
(I guess I should say... I've cocked the hammer on my ARs before and watched the pin roll)
Hmm, I'll have to go check mine. Still, I don't believe it to be a real problem
Hmm, I'll have to go check mine. Still, I don't believe it to be a real problem
Might not be.
Hmm, I'll have to go check mine. Still, I don't believe it to be a real problem
Have been told by a few Industry Pros that it would take around 1.5M trigger pulls to wear the anodizing with the pins.
Have been told by a few Industry Pros that it would take around 1.5M trigger pulls to wear the anodizing with the pins.
Yep. A lot of guys buy the KNS pins thinking they're saving their lower. But every time that comes up, several prior service guys will note the ANCIENT M16s they saw in the military racks that are still going.
Obscenejesster
04-22-14, 16:02
Have been told by a few Industry Pros that it would take around 1.5M trigger pulls to wear the anodizing with the pins.
Im not really worried about my FCG holes egging out. Like you said, it takes more trigger pulls than I could ever put on it and is it ever did happen, there are fixes for it.
I can see why someone would want to use them on an 80% lower that was only Cerakoted and not Anodized. I don't think Cerakote is as hard as anodizing.
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Obscenejesster
04-22-14, 16:09
I don't think the original style pins are likely to rotate in the receiver. The springs put a bit of pressure against the pins and there is a bit of natural sticktion when it's steel & aluminum. It only makes sense to size the pins & holes so the harder hammer & trigger rotate around the pin than to have the pin to rotate in the aluminum receiver and cause fretting.
The pins fretting in the receiver isn't a problem, otherwise we'd be complaining about all the threads concerning the use of steel bushings to repair worn pin holes
Look closely at your pins as you cock the hammer and press the trigger. The hammer pin will rotate with the hammer due to the J-Spring inside the hammer that captures the pin.
When pressing the trigger, the trigger pin will rotate slightly but not nearly as much as the hammer pin. It pretty much just rocks back and forth.
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Leaveammoforme
04-22-14, 22:27
I can see why someone would want to use them on an 80% lower that was only Cerakoted and not Anodized. I don't think Cerakote is as hard as anodizing.
This is where I see KNS pins as beneficial. Not necessarily from wear issues but from out of spec issues. When people see the .156 pin hole spec and ram a 5/32 (.15625) drill bit through the lower that actually makes a .158ish hole not realizing that there wont be a level 3 anodize to build the surface back somewhat. Then they install .154 pins and wonder "why so much slop?" KNS pins will actually keep the trigger to hammer relationship at the right distance.
soldier_twiggy
04-22-14, 22:36
When I ran the test fire pit for a local AR builder, a few of our OLD test lowers were a little "wallered out" (that's a technical term) and were continuously breaking hammer pins and having trigger pins drift. We installed KNS pins and stopped that problem.
That being said, some of these lowers saw 300-1000 trigger pulls 5 days a week for years before they started failing. So I don't think KNS pins are necessary unless you get paid to shoot 24/7, like Jerry Miculek.
essayons
ive got a lower that you can physically see the factory pins moving up and down in and not just rotating.Ill be honest and say Ive never actually paid attention before and I dont have another rifle with a factory trigger in it to compare.Only reason I looked close enough is because the pins always seem to stick out of one side of the receiver or the other and I can push them a small amount.The trigger spring is installed correctly and the lower is factory assembled
how much movement would actually be considered normal? lol
It's just a .22, but I've got an M&P15-22 (polymer lower) that occasionally stops functioning when one of the hammer/trigger pins walks out and the FCG gets bound up. KNS pins are a cheap, easy fix for that issue. I wouldn't expect that kind of thing to happen on an in-spec metal lower. To me it is a possible solution when there is a known problem, but not something I'd do preemptively.
soldier_twiggy
04-22-14, 23:18
ive got a lower that you can physically see the factory pins moving up and down in and not just rotating...Only reason I looked close enough is because the pins always seem to stick out of one side of the receiver or the other and I can push them a small amount...
how much movement would actually be considered normal? lol
Not that much! If your pins are walking, they're too loose. And if the pins ends will move vertically and horizontally, you're looking at future broken pins and weapon failures.
Could be a FCG hole size problem, but I'd be more inclined to check out the pins themselves. I'll bet they're on the small side.
Out of curiosity, what make FCG and Lower are we talking about?
essayons
Not that much! If your pins are walking, they're too loose. And if the pins ends will move vertically and horizontally, you're looking at future broken pins and weapon failures.
Could be a FCG hole size problem, but I'd be more inclined to check out the pins themselves. I'll bet they're on the small side.
Out of curiosity, what make FCG and Lower are we talking about?
essayons
to be perfectly honest Im not going to name the company without giving them a chance to make it right.I wasnt even sure if it was abnormal or not as ive never paid attention very closely
ill upload a short upclose video
soldier_twiggy
04-22-14, 23:32
to be perfectly honest Im not going to name the company without giving them a chance to make it right.I wasnt even sure if it was abnormal or not as ive never paid attention very closely
ill upload a short upclose video
That's cool. I wasn't looking to bash based on name. Was planning on checking Google to see if that was a common issue with their FCG's or lowers. Best of luck.
essayons
When Bill Geissele speaks, I tend to listen. If he thinks the KNS pins are a bad idea.... well, that's a good enough reason for me to stay away from them :)
They look tacticool that is all that matters.
I was doing pin observation last night. The hammer pin slightly moves when the hammer cocks... then the pin spins forward on each hammer drop. No way am I messing with the natural parts movement by installing this nonsense.
soldier_twiggy
04-24-14, 13:32
Both my hammer and trigger pins on my 7.62 DPMS just "rock" with the movement...neither really "rotate".
Whereas the hammer pin on my Bushmaster (Windham) rotates about 10* each hammer stroke. And the trigger pin doesn't move at all it seems.
essayons
Leaveammoforme
04-24-14, 13:41
Both my hammer and trigger pins on my 7.62 DPMS just "rock" with the movement...neither really "rotate".
Whereas the hammer pin on my Bushmaster (Windham) rotates about 10* each hammer stroke. And the trigger pin doesn't move at all it seems.
essayons
Your Windham should have an FA bolt. Therefore, 1 step higher than a bushmaster. Not quite a 100% gun but definitely a step up from old school BM's.
soldier_twiggy
04-24-14, 13:46
Your Windham should have an FA bolt. Therefore, 1 step higher than a bushmaster. Not quite a 100% gun but definitely a step up from old school BM's.
It is an old school Bushmaster. It came with a SA BC, but I've since converted it to a CMMG piston, which swaps to a FA one piece carrier.
essayons
Took a look at my carbine. It is a PSA lower with the SSA trigger installed. Pins rotate with both the hammer & trigger. Whaddya know 'bout dat?
Don't mess with nature. ;)
soldier_twiggy
04-25-14, 09:41
Don't mess with nature. ;)
AR15, the true king of the jungle?
essayons
When Bill Geissele speaks, I tend to listen. If he thinks the KNS pins are a bad idea.... well, that's a good enough reason for me to stay away from them :)
Agreed, though in fairness I believe I read that KNS is making pins (upcoming) that will be properly hardened for use with G triggers.
Obscenejesster
05-01-14, 17:21
Agreed, though in fairness I believe I read that KNS is making pins (upcoming) that will be properly hardened for use with G triggers.
I don't believe it has anything to do with pin hardening. KNS already hardened their pins some time ago.
It is because the KNS pins are slightly smaller than the G pins. The biggest conflict comes when using the KNS pins with the High Speed Trigger due to the C-Clamp.
http://i978.photobucket.com/albums/ae266/jrwingate6/Geissele_pins_zpsc6ad7704.jpg (http://s978.photobucket.com/user/jrwingate6/media/Geissele_pins_zpsc6ad7704.jpg.html)
http://i978.photobucket.com/albums/ae266/jrwingate6/KNS_pins_zps8990cc8c.jpg (http://s978.photobucket.com/user/jrwingate6/media/KNS_pins_zps8990cc8c.jpg.html)
Leaveammoforme
05-01-14, 18:03
*stumble* *drop my briefcase containing TOS literature*
4/16/2009 11:47:53 AM
just oil them as you would any other std. pins.
Really, markm is the man to ask about this. He's a KNS god.
It's just a .22, but I've got an M&P15-22 (polymer lower) that occasionally stops functioning when one of the hammer/trigger pins walks out and the FCG gets bound up. KNS pins are a cheap, easy fix for that issue. I wouldn't expect that kind of thing to happen on an in-spec metal lower. To me it is a possible solution when there is a known problem, but not something I'd do preemptively.
That's similar to my thoughts regarding these pins. They are not necessary unless you have a specific need for them or your lower starts having issues.
If they were truly necessary, you'd see all the Military M4's/M16's with them from the factory. I've never seen one that does...
If they were truly necessary, you'd see all the Military M4's/M16's with them from the factory. I've never seen one that does...
Not true. At ~1,000,000 trigger pulls before wearing out (probably a low estimate), it'd be easier to simply replace a lower receiver for $100-200 than it is to absorb the extra $5, $10, $20 - whatever it is - cost per every carbine the military buys. Most of them don't see that many rounds in their lifetime and would not be close to wearing out, so it's a saved cost.
The military does not always do things the best way, they simply attempt to do them the way that's most effective with how they currently operate.
Not true. At ~1,000,000 trigger pulls before wearing out (probably a low estimate), it'd be easier to simply replace a lower receiver for $100-200 than it is to absorb the extra $5, $10, $20 - whatever it is - cost per every carbine the military buys. Most of them don't see that many rounds in their lifetime and would not be close to wearing out, so it's a saved cost.
The military does not always do things the best way, they simply attempt to do them the way that's most effective with how they currently operate.
That's what I mean.
Most civilians will never shoot that many times to need Anti-rotation pins to begin with. If Military-issued rifles don't use them, then much less a civilian who shoots less.
wildcard600
05-02-14, 07:34
That's what I mean.
Most civilians will never shoot that many times to need Anti-rotation pins to begin with. If Military-issued rifles don't use them, then much less a civilian who shoots less.
But the if they indeed COULD save a lower from wearing out then the additional cost to the civi shooter could be justified by many shooters eg Pre-ban lowers in certain states or registered M16 lowers.
That's what I mean.
Most civilians will never shoot that many times to need Anti-rotation pins to begin with.
The KNS pins are likely to cause more problems before that anyway. There is NO NEED for fixed pins.
A high volume of fire on a fixed pin might lead to a pipe cutter effect on the pin. Then when that pin fails, it could yaw and deform the lower's pin hole.
Fixed pins are just retarded bullshit nonsense.
Wolfpack45
05-02-14, 07:38
I have one lower that after a series of unfortunate events ended up a little out of spec and trigger pins would walk out. That lower now has a set of KNS pins in it to remedy the problem. Other than that one though, all my other rifles have the standard pins in them with zero issues. So with the exception of using it as a fix for walking pins, I see no use for them.
If military weapons are unaffected by the so called rotation problem so are civilian registered M16's. 99% of those that own these guns will never put the amount of rounds or abuse on them to even make a difference.
But the if they indeed COULD save a lower from wearing out then the additional cost to the civi shooter could be justified by many shooters eg Pre-ban lowers in certain states or registered M16 lowers.
wildcard600
05-02-14, 15:23
If military weapons are unaffected by the so called rotation problem so are civilian registered M16's. 99% of those that own these guns will never put the amount of rounds or abuse on them to even make a difference.
hence the use of IF and COULD in my post.
besides most military rifles wear out from cleaning rather than shooting it seems.
Notice I said abuse. Abuse also means dissembly and assembly in an incorrect manner, with incorrect tools.
hence the use of IF and COULD in my post.
besides most military rifles wear out from cleaning rather than shooting it seems.
wildcard600
05-02-14, 15:33
Notice I said abuse. Abuse also means dissembly and assembly in an incorrect manner, with incorrect tools.
i guess you have more faith in the average gun owner than i do.
Quite the opposite actually and not sure how you drew that conclusion.
i guess you have more faith in the average gun owner than i do.
Obscenejesster
05-02-14, 18:19
Didn't mean to start an argument over some pins. Personally, I think some of the problems people say KNS pins cause are just hearsay.
Personally, I think some of the problems people say KNS pins cause are just hearsay.
I think the problems they solve are hearsay.
Obscenejesster
05-03-14, 11:01
I think the problems they solve are hearsay.
That could be. I'm just wondering where all the pictures of the messed up lowers are.
Notice I said abuse. Abuse also means dissembly and assembly in an incorrect manner, with incorrect tools.
Is there a "proper" tool or method for replacing the trigger and hammer pins? I always thought it was simply using a punch (or similar object) to knock the pins out, as they're simply held in by spring tension.
I'm not sure if your being obtuse for a reason or you simply don't know. There is a correct sequence of disassembly for starters. Some punches work better than others (beveled edges) as opposed to using flat steel punches. I have also seen people use the wrong size and/or just pound them out.
Is there a "proper" tool or method for replacing the trigger and hammer pins? I always thought it was simply using a punch (or similar object) to knock the pins out, as they're simply held in by spring tension.
I considered KNS pins - seems like you see a lot of rifles in the various AR threads/forums with them. Then I did some research and it seems most favored the "not really necessary" argument, while some fell into the "probably not needed but cheap insurance" argument. Very few seemed to fall into the "must have" camp, which was odd considering how many picture threads have rifles with anti rotate pins in them. There may be a "taking pictures vs shooting your rifle" metaphor in there somewhere :). Anyway, I installed a Geissele SSA and Geissele advised not to use them, so it became an easy decision :).
"probably not needed but cheap insurance" argument.
Those are the dumb asses who bought Registered lowers and think they're protecting them.
Most bought them because they had money to burn accessorizing the piss out of their new toy.
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