anti-rotation pins AR15

[panther76]

Recently I had my hammer pin on my AR-15 break in two while I was firing. Rifle is less than two years old, lower was Spike's Tactical. I had standard USGI hammer/trigger pins. I felt that I didn't need anti-rotation pins, and for strictly .223/5.56 use you might not. However, I've been using the rifle with a Spike's .22lr adapter kit.

These adapters (most) are just a blowback operation similar to some of the 9mm AR-15 style carbines. Very easy to use, worked like a charm once I got the right recoil spring in it. However, apparently even with .22lr the blowback really beats up the lower. My hammer pin sheared in two, and while I haven't measured it yet to see how much, it appears the holes might be worn a little. Lesson Learned. Thought I'd spare others the same stupid mistake I made.

I will probably be fixing replacing the pins with a KNS precision anti-rotation pin set.

[wa3ra]

Is that a cast pin? I'll bet if you look at the break, one side has a cup and the other a protrusion. If so, it was a casting flaw, and would have happened even without the 22 conversion.

The precision anti-rotation pin is a good idea, and cheap insurance.

[arjohnson]

Recently I had my hammer pin on my AR-15 break in two while I was firing. Rifle is less than two years old, lower was Spike's Tactical. I had standard USGI hammer/trigger pins. I felt that I didn't need anti-rotation pins, and for strictly .223/5.56 use you might not. However, I've been using the rifle with a Spike's .22lr adapter kit.

These adapters (most) are just a blowback operation similar to some of the 9mm AR-15 style carbines. Very easy to use, worked like a charm once I got the right recoil spring in it. However, apparently even with .22lr the blowback really beats up the lower. My hammer pin sheared in two, and while I haven't measured it yet to see how much, it appears the holes might be worn a little. Lesson Learned. Thought I'd spare others the same stupid mistake I made.

I will probably be fixing replacing the pins with a KNS precision anti-rotation pin set.

22's are much harder on hammer pins than a 5.56 is, so the KNS pins will help a bit.

[orionz06]

22's are much harder on hammer pins than a 5.56 is, so the KNS pins will help a bit.

Interesting.

[forceinPA]

Interesting.

So, I guess a 50 BMG would just about blow them clear out the lower. Anti- rotation pins are for full auto switches. Pins are pins

[arjohnson]

So, I guess a 50 BMG would just about blow them clear out the lower. Anti- rotation pins are for full auto switches. Pins are pins

Go do your research on delayed versus direct blowback then get back to me

[forceinPA]

Go take an armours course and get back to me

[arjohnson]

Go take an armours course and get back to me

Since you took a armorers course you should be able to help out the OP.

I also know KNS pins are a solution to a problem that don't exist when it comes to 5.56, they have however been quite useful in the 22 and 9mm AR's due to the direct blowback, which is much harder on your hammer & trigger pins than a 5.56, but you should already know that since you took a course.

[forceinPA]

Old wives tail,or internet lore. Prove where it is more harder than a DI system. It doesnt. Your punny 22 is harder on the pins than a 458 socom ,Or even the 556 rd is pure hogwash. The blowback in 9mm might have a slight increase, but it also; due to the blowback design have more felt recoil than the 556. we are talking about a sheared pin ,not just pin rotation. The pin more than likley, as stated by another poster had a flaw, which failed. it had nothing to due with blowback.

[forceinPA]

Since you took a armorers course you should be able to help out the OP.

I also know KNS pins are a solution to a problem that don't exist when it comes to 5.56, they have however been quite useful in the 22 and 9mm AR's due to the direct blowback, which is much harder on your hammer & trigger pins than a 5.56, but you should already know that since you took a course.

Wrong again, I have had my pins rotate out on FA 556. When firing on fa over time the pin holes can get oblong or just plain larger, and the pins will walk out.