Are KNS Pins for your AR a gimmick?

[JohnO]

I've seen them on people's blasters. Same folks who would have the kitchen sink on their rail if it was 'cool'. I'm just trying to understand if they offer any real benefit.

KNS website says:

They are the toughest pins produced. We designed our pins to withstand the stresses generated by high-impact suppressed fire. Our trigger & hammer pins are stainless steel and our retainer sideplates are steel with a black nitride finish.

Our KNS non-rotating trigger/hammer pin sets prevent wear on your AR lower and prevent your pins from walking out of your receiver.

I would think proper gas port size & buffer system would be more important for mitigating stress. I've never experienced AR pins walking out.



https://www.midwayusa.com/product/1003368197

Product Overview
For protecting a valuable select-fire receiver, or even a semi-auto receiver that has seen a high volume of fire, these non-rotating trigger and hammer pins are a must. Anti-creep retainers keep the pins from constantly rotating during extended firing sessions and weakening the receiver walls. The 0.154" diameter option is for use with Standard Small Pin receivers with enlarged hammer and trigger pin holes. Modification II pins retain the popular original "dogbone" look of Generation I pins, with added strength for longevity. Not compatible with Jewell match triggers.

[OlongJohnson]

The argument there is that the pins rotating are going to wear out the holes in the receiver. If the pins are properly ground and polished like they should be and the receiver holes are properly machined (very smoothly drilled or reamed) and anodized like they should be, that is literally the last thing I would worry about on the gun.

The pins should be held in the gun by the trigger springs interacting with grooves machined in them. If that doesn't work, it's probably because the grooves weren't cut right or the springs aren't as strong as they are supposed to be. If the holes are not perpendicular to the receiver and parallel to each other, that might also cause a variety of problems including and in addition to the pins taking a walk. I had the takedown pin walk out repeatedly on my LCP Custom and it turned out the entire upper was machined fubar.

If your lower and/or trigger pins were made wrong in the first place, the KNS pins might be a solution.

Disclaimer: I'm not an armorer, firearms manufacturer representative, or military-experienced user of ARs. Just a regular mechanical engineer who figures out why things don't work right and fixes them.

[HCM]

I've seen them on people's blasters. Same folks who would have the kitchen sink on their rail if it was 'cool'. I'm just trying to understand if they offer any real benefit.

KNS website says:



I would think proper gas port size & buffer system would be more important for mitigating stress. I've never experienced AR pins walking out.



https://www.midwayusa.com/product/1003368197

They have a purpose, actually two related purposes. Outside those purposes they are unnecessary.

On high round count guns with worn pinholes that you don’t want to /can’t scrap - like a registered transferable machine gun.

On ARs in calibers which are direct blowback such as pistol calibers and .22 LR because the AR was not designed to be direct blowback and it’s hard on lowers and lower components. The uneven force can mske the steel pins “egg out’ the previously round pin holes in the softer aluminum of the receiver.

[CleverNickname]

I've got a set on my M16. Maybe it's a gimmick, but $30 to save a gunsmith having to weld up and re-drill the FCG pinholes if they got worn seems like a fair trade. I do mostly shoot 9mm (and .22LR) out of it.

[Pnut]

My understanding is that they were meant for full auto rifles, where the lowers receive heavy pounding at a high rate of speed.

[Magsz]

They're relatively cheap insurance but they're by no means necessary unless you're running the following:

An m16.
A 9mm Blowback AR
A violently overgassed suppressed AR
A worn out lower.

Other than that, most lowers will be good for a lifetime of use without them provided you're using in spec pins in the first place.

[mrozowjj]

The only other time they are necessary are if you have a drop in trigger that is like an all in one trigger pack. With a pack like that the pins won't stay in because they have no spring tension.

A lot of those triggers come with something like that but not all of them.

[BWT]

They have a purpose, actually two related purposes. Outside those purposes they are unnecessary.

On high round count guns with worn pinholes that you don’t want to /can’t scrap - like a registered transferable machine gun.

On ARs in calibers which are direct blowback such as pistol calibers and .22 LR because the AR was not designed to be direct blowback and it’s hard on lowers and lower components. The uneven force can mske the steel pins “egg out’ the previously round pin holes in the softer aluminum of the receiver.

Given your background- something that never made sense.

How do the KNS pins reduce/prevent this wear from the same energy being exerted on a pin. The pin will no longer rotate, yes. But the lower is still aluminum, and the pins are still steel.

I have seen this same commentary over the years and how the pin being able to rotate or not preventing wear seemed unrelated.

I don’t know if you have specific knowledge on this subject but figured there was a decent chance you did.

[HCM]

Given your background- something that never made sense.

How do the KNS pins reduce/prevent this wear from the same energy being exerted on a pin. The pin will no longer rotate, yes. But the lower is still aluminum, and the pins are still steel.

I have seen this same commentary over the years and how the pin being able to rotate or not preventing wear seemed unrelated.

I don’t know if you have specific knowledge on this subject but figured there was a decent chance you did.

They are “anti walk pins” not anti wear pins.

They don’t stop all wear -stopping rotation reduces some wear but they don’t stop uneven wear (egging) from blowback operation.

What they do accomplish is keeping the pins in place (not walking out under recoil) and functioning after the friction / slip fit is lost.

[nycnoob]

I've never experienced AR pins walking out.

Was in a class last month and the guy next to me had two pins walk out, one all the way and one needed to be pushed back in. The gun was not usable at that point. I was not paying too much attention, but they had the right equipment to fix it and had him back on the line in no time.