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Assembly pin?

5231 Views 14 Replies 8 Participants Last post by  marlin336
So far I have not experienced any problems with my P3AT assembly pin walking out. However I believe in being prepared. I ordered some new assembly pins and they should arrive this week, along with other spare parts and magazines.

I am planning to do the cut and screwdriver slot as described at

However I got to wondering if the assembly pin is designed to rotate? I haven't seen this question addressed on any of the Kel Tec sites. I took some laquor thinner, cleaned the grease from the head of my assembly pin and applied a dab of my wife's nail polish to a spot on the edge of the pin. Then I noted the paint spot location and manually cycled a few rounds though. Guess what? The assembly pin rotates about a sixth of a turn CCW with each cycle.

Of course if I slot the pin as described above, the pin will not rotate anymore. Will a few hundred or thousands of rounds banging the barrel against the now frozen assembly pin do any sort of damage? I know the pin in my 1911, Karh Arms, etc. doesn't rotate, but perhaps it's designed differenty?

Could that be the reason Kel Tec won't slot the production assembly pin? Or conversly, could the rotating assembly pin be the reason that problems don't show up until a couple hundred rounds go through the weapon? Seems to me a rotating steel pin in an aluminum hole might not be a good idea.

Anyone have experience with a slotted assembly pin that's had a thousand rounds or more of use? I plan to practice frequently. I believe in shooting a lot.

Keep shooting.
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Now that's a good point!
I could very well BE that a rotating assembly pin accelerates wear in it's frame holes...
I doubt that the rotation of the pin has anything to do with function...
You've certainly given us something to think about, however!
Outstanding observation! Sounds like a good question for the guy who designed the pistol.
Ask the questions

If anyone knows someone at Kel Tec or anywhere else well enough to ask these questions, go ahead and do it and post the answers here. I don't post on that other site and I don't know who to ask, but I'd sure like to see these questions answered by someone in the "know."


Keep shooting
I have actually thought about that before I ever did or posted it...

but then thought about the P-11 design. Same basic principal and the pin does not rotate. Not only that, but it seems that the pins in the P-11's seem to not pop out as much. I have also not had a problem with mine and can't think of a reason it would have to, but could see that the rotation may play a part in why they pop out to begin with.

I will add though that if you don't have the lug area of the barrel smooth and lubed as well as the pin, then the lug will try to spin the pin, and theoretically this could still spin it and cause the pin to be rotated out of position. But mine is smoothed, lubed and never spins.
The thing I think about is possible uneveness in the surface of the pin; areas that aren't completely rounded.
If the pin spins, this is going to eventually wear the frame holes...

Flyer and yzguy, the frame hole wear is, of course, one possibility.

Or could the rotation wear down the small shoulder of the pin itself that the spring rides against. If this shoulder becomes rounded, from lack of lubrication, build up of dirt, improper SANDING during the fluff and buff, etc. then the pin could slip out past the spring as it rotates.

I know the barrel lug on my Kahr is shaped similiar to the P3AT, but of course it's slide stop is a totally different design. But after over 3,000 rounds through my Kahr 9mm the pin has became loose in the slide stop and it now rotates. I contacted Kahr and they said this was normal and wouldn't do anything about it.

I still think yzguy's slot and screwdriver idea is probably the best approach. But I still wonder????

Thanks for the idea's

Keep shooting.
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I don't think the pin rotation was a plan in the design of the pistol. The rotation makes sense though when you think about how the lug on the barrel makes a downward and rearward motion during firing or cycling. I think the interaction of the lug on the pin is what creates this rotation.

I agree with Flyer, the rotating pin could create wear in the frame holes. A fixed pin would most likely cause increased wear to the pin itself -- a more attractive and easily corrected issue in my book...assembly pins could be cheaply replaced after every 500 rounds or so. Trying to correct worn frame holes would mean sending the bugger back to KT for a frame replacement under warranty.

The pin is fixed in the P-11/40/357 -- but primarily because of the design to keep it flush with the frame and grip. Whereas, the pin head on the P-32/3AT protrudes slightly (it also looks like it take fewer machining steps). Haven't we heard of assembly pins backing out on the P-11/40/357? It hasn't happened to me on any of my pistols, but I thought I remember some having difficulty...
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yeah, there have been a few that have had pins back out of P-11's and/or P-40's but not as often. I also deepened the groove in the pin for my P-11, but the down side is that I need a small screw driver now to push the spring down to get the pin out. (I can still turn and remove the P-32 with a case rim). To me this is a small price to pay to make sure the pin will not come out.

Also if the pin starts to come out in the P-11's it will lock the slide back....
The pin on the left failed (slipped out) and caused some damage. This happened to another P3AT owner.

My original pin in the middle never came all the way out. It just had too much play with the long neck. This did not leave much pin holding on the right side of the frame when it slipped out to the edge of the cut.

The new one from Kel-Tec on the right seems to have incorporated the pin fix that some folks have used to keep their pins from slipping out during firing.
Mine appears to be of the type on the left with the beveled shoulder. I have experienced no pin walk with it.
New Pins

Got some new Assembly Pins, Magazines and other spare parts from Kel-Tec. The new pins appear to be the same as the one on the right of marlin336's excellent picture. My orginal pin appears to be just like the one on the left of 336's picture. My P3AT was ordered in October and delivered in early January, serial # H2TXX. So it appears to me that Kel-Tec may have made a design change in the new pins.

One thing I noticed right away. When inserting the new pin there is a nice loud "click" as the pin goes fully into place. Also it seems to require approximately twice the effort to remove the new pin. And the new pin appears to be machined much smoother than the old pin.

I plan to try the new pin and magazines within the next week. I think I'll run a hundred rounds through while using one of the new pins. I'll also be looking for smiley's on the new magazine followers. Don't think I'll find any since my last rampectomy attempt. Hope I don't find any on the bullet nose either.

I'll probably cut a grove and screwdriver slot in the old pin and use it until it's worn out, but it's nice to see Kel-Tec appears to be trying to correct the problem.

Keep shooting
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looks like they made the shoulder more squared first, but in the first batch did it at the wrong spot in the pin (middle pic) but now have the shoulder at the correct position. The only problem is that this same shoulder holding it in, must be able to be overcome by simply pulling on the pin, which is why their used to be an angled shoulder. I still like my slot better. It 100% firmly holds it in one spot (I CAN NOT pull it straight out), and is held in this spot by spring pressure, but if you just turn it, it slides out pretty easy.

I could see problems happening from the new pin if the shoulder was just a tad to deep. When you TRY to pull it out, it could take the side of the grip (just bow it out a bit) or the spring out with it.
Latest production P-3ATs will have the deepened shoulder on the assembly pins, irrespective of the increased difficulty in its removal during disassembly.

Confirmed it on the H4xxx I saw today at the gun shop.

ppmd - who heard it straight from the horse's mouth
New Assembly Pin

Tested the new pin (the pin on the right in previous picture) today with 75 rounds. There was no pin walking at all.
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