AR15 hammer pin rotates in frame

[boing]

Disclaimer: I'm laid up with a broken ankle, so I have a lot of time think about stuff like this for the next six weeks.

The hammer pin in my Bushy rotates in the frame as the hammer is cocked and released. It has about 1500 rounds through it. My understanding is that this is less than desirable, as the steel pin wears on the aluminum frame, elongating the hole. The hammer should rotate on the pin (steel on steel), while the pin stays put in the frame. My rifles are strictly low-usage items, so I don't expect any problems with frame wear in my lifetime, but if I wanted to fix this issue, how would it be done?

I chucked the pin in a drill and polished the hammer bearing surface, but it didn't work. I'm wondering what the "gunsmith tricks" are for making this problem right (not that it really needs it, but anyway...)

Thanks

 

[4v50 Gary]

A pin rotates because it has space. Polishing it creates more space. You might want to replace the pin. Otherwise, I suppose you could remove the pin and take a punch and peen it slightly to widen it. Mic it first and after and then reinsert. Touch up before installing. Mind you, it'll look scarred.

 

[444]

http://globaltactical.com/axami/shop.php?grd=117&prd=120

I had a problem with one of my lowers where I would fire about a dozen rounds and the gun would quit working. It would take me a minute to realize that the trigger pin would vibrate until it fell inside the receiver. The above link will take you to the solution to both of our problems. These are very popular with the full auto crowd but I put a set in two of my guns and I think I am going to do the rest.
This set of pins was very well thought out. They are obviously threaded on each end. They come with a pointed piece you screw into the end of each pin. You then drive the old pin out and the new pin in with the pointed attachment. You can replace your current pins in seconds without taking anything apart. These new pins also have a hole running crossways through them so you can put oil in the hollow pin and it will gradually seep out onto the bearing surface.

 

[4v50 Gary]

Take your calipers and get the measurements for the receiver hole. I wonder if they're non-mil spec. Also mic your hammer pin. Something has to be out of whack.

 

[444]

I am not saying you shouldn't do all that, BUT, this is not unusual at all. Obvioiusly there are people making parts to correct the problem and these parts sell like hotcakes. You are not alone. This isn't a unique situation.

 

[boing]

That KNS kit is interesting, but it looks like a complicated way of fixing something that should be right in the first place, using the standard parts (assuming they're in spec).

Gary- I didn't polish the ends of the pin, just the middle where it contacts the hammer. The ends of the pins measure around 0.153+, and the holes are right at 0.155, and are not out of round.

I hesitate to peen the existing pins unless I could be sure they maintain a uniform diameter. Wouldn't a simple set of oversize pins solve the problem?

 

[444]

So buying a set of pins that can be ordered in a couple different sizes which install in about two minutes is complicated.
But all the work you have done and are thinking about doing isn't ?

Ok.

 

[boing]

Am I wrong, or do I see cap screws, loctite, external retaining struts, and hollow pins with "special holes" for lube?

And what is "all the extra work" you think I'm doing or planning to do?

Yes.

 

[444]

Ok, I guess it is obvious that you want to do this a different way and it is none of my business how you do it. I am not trying to argue with you.
But, you have a problem that a lot of other people have had. Someone designed and built a fix for the problem. It is recognized in the AR15 community as the fix for your problem. I just thought I would mention it.

Yes you see those parts. None of that is complicated in the least. IMO (and in the opinion of a lot of other people) these pins are not only a fix for your problem but an upgrade to the weapon. They do more than the original pins and perform the function of the original pins better than the original pins.

The extra work: when you took the pins out and put a mic on them, you did more work than was required to put in these new pins.

Please don't let me get on your nerves. That wasn't my intention. I hope your project turns out beyond your wildest dreams.

 

[boing]

I'm sorry, 444. I took your post as "This is only answer to the problem. Period." I have no doubt that it does solve the problem, but you're right: I do want to do it another way. I want the original parts to do the job they're supposed to do. I'm assuming it's possible, or M16s and M4s would be falling apart in short order with damaged lowers. Maybe it's just more trouble than it's worth to fit the parts "properly", as compared to the after-market solution. That's certainly true enough for any number of other designs.

Thanks for your suggestion.