What causes guide rod hole/guide rod peening?

Discussion in 'P-3AT' started by catsize, Apr 19, 2008.

  1. catsize

    catsize New Member

    Aug 17, 2006
    Well, I went to the range today, first time since getting my new replacement slide back from Kel-Tec (the original slide had peened around the guide rod hole). Prior to going to shoot, I cleaned and lubed the gun and installed the famous JFB washer. I also put on one of sprinter's grip covers (highly recommended, by the way!).

    At the range, I put 150 rounds of Remington UMC ammo down the pipe. The gun did not malfunction in any way, even once. It shot clean and crisp and I actually got some pretty good groups at 7 yards during rounds 50 - 100 (I was getting used to the sights for the first fifty rounds and suffering some serious hand fatigue for the last fifty!). But, as this was a function test, I didn't consider accuracy important. I just wanted to see if the gun worked and whether or not the gun evidenced any signs of peening.

    Now, when I got home and disassembled the gun for cleaning, I noticed two things: 1) The guide rod hole seemed to be slightly deformed (elongated at the bottom edge) and showed some *very* slight signs of peening in the same area.

    Also, and this was a bigger surprise, the head of the guide rod, where it sits in the notch in the barrel, had peened! It was flat on the side that contacted the barrel.

    Personally, I've never seen or heard of the head of the guide rod peening. Has anybody else experienced this? Is it a problem? Do you think it was caused by the installation of the washer?

    I really don't understand what's happening -- With the washer installed, shouldn't the nominal thickness of the guide rod hole be increased, thereby eliminating the possibility of peening?

    If someone can explain what it is that causes the two types of peening described above, I'd appreciate it very much. If what I've described don't seem to be issues, I'd be very happy to just live with it, as the gun functions perfectly. But, I'm afraid that function *will* be affected, if the peening gets any worse.

    Any help would be greatly appreciated -- Thanks!
  2. PshootR

    PshootR Banned

    Apr 1, 2005
    The heads of Kel-Tec guide rods all show some sighs of wear IMHO. The steel ones like those used in the P-40 & P3-AT are worse than the polymer ones in the P-11 and P-32. They hit the bottom of the barrel in use. The peening of the guide rod head does not seem to cause a problem, though.

    The steel guide rod can cause elongation of the guide rod hole in the front of the slide.
    Maybe Packer or someone will offer a cut off and turned down P-11 guide rod for the P3-AT.

  3. JFB

    JFB New Member

    Jul 25, 2005
    first, as PshootR explained, the head of the guide rod is "worn" as the barrel slides over it durring recoil.  what i've done is to scribe the end of the head with a line just above the barrel lug, when it was installed in the slide.  I use this to ensure i put it back exactly the same each time, thus the head will wear as needed for the barrel to slide by and only have one worn spot. I've also slightly filed mine so it has that waning moon profile like a 1911s spring guide

    another thing with the head.  the rod tilts during recoil, this up and down motion of the rod will cause the head to work back and forth slightly and dig a hole in the frame.  The displaced frame metal can form a lip, and hold the head from slide out of the frame at disassembly.

    The rod tilting is caused by the hole in the rod not being in the same elevation as the rod head as held by the frame. the hole in the slide is like a bushing, if the clearances are small and the length of the fit is long, the tilting rod will touch at opposite verticle points and thus wear the bushing into an hour glass shape with the outside ends being an oval.  thus the round hole as made during manufacturing has to became a very sligth oval and a little wear is expected.

    The magnitude of this wear pattern is determined by whether or not the bearing surfaces of the slide hole are suffcient to with stand the sliding and hammering of the rod.  if not, the hole in the slide will show peening and keep getting larger.

    now, you say you have the nylon washer installed.  the reasoning behind using one is to provide a longer bushing to provide sufficeint bearing surface, but be flexable so it does not take the permenant hour glass shape as the rod tilts.  if the slide hole is providing  suffecient bearing surface, the nylon should be flexing.  if the distance between the nylon point of rod contact and the hole in slide is not made as close as possible, this would be like having a long bushing and the point of where the minimun diametr of the hour glass wear occurs depends on the resistance of the end material.

    The "lenght" of the bushing can be long if the 1/4" hole in the slide has a tappered drilled bottom and the washer installed with out tappering the larger OD to match so it can be inserted into that tapper (or inserted with the smaller od into the tapper)
  4. catsize

    catsize New Member

    Aug 17, 2006
    PshootR and JFB, thank you for the responses -- They're very helpful!

    JFB, your reply contains a lot of information, but I'm not quite sure that I understand one bit: You say that

    Does this mean that the washer can be too long, if it is not filed to fit the tapered guide rod hole? I have installed the washer "backwards," without shaping, so that the little "chimney" fits inside the tapered guide rod hole. The fit is dead solid perfect and it looks like a part of the original slide. There is no gap whatsoever between the washer and the slide.

    If I'm reading your post correctly, it seems that the extremely slight elongation of the hole may be perfectly normal and that it may not increase further, as the washer is providing a flexible bushing that keeps things in line. After 150 rounds my last slide looked exponentially worse than the new one looks now. So, maybe the new one was just "breaking in" and this is what it's going to look like for the rest of the gun's useful life?

    Sorry if I seem a little dense. But, now I understand the reason for the hole peening and I'm thinking the washer is doing it's job. Am I correct?

    As to the guide rod itself -- Thanks for the info. The flat side of the guide rod head is pretty obvious, so I'll just rotate it to make sure that side faces the slide when I reassemble after cleaning.

    Again, thanks!
  5. JFB

    JFB New Member

    Jul 25, 2005

    imagine sticking the end of a broom handle in a fairly good fitting hole drilled in two sheets of 1/2 plywood held together. you can easily lift the end of broom several feet up and down. now space the sheets 12" apart and insert the broom handle, you might be able to lift it an inch or so.

    the way you installed the washer has the lenght of the fit the sum of the metal and washer. If you did it the other way the washer would not slide into the tappered bottom and thus seperate like the above plywood. BUT any way, the nylon will give and the rod tilts the same, the metal will carry more load than the nylon and do the same job as if it washer was not there, the nylon will reduce the load on the metal and absorb some of the boncing around. so no problem with that, other than possibly wear out the washer

    The problem with having the washer spaced from the metal would be that it reduces the space available for the spring as it compresses. the slide should contact the frame before the spring goes coil to coil. I know on mine, the washer removed enough spring space that it goes coil to coil BEFORE the slide contacts the frame. This has caused my outer spring to have one coil stretch and put a little kink in it
  6. jerry-s.

    jerry-s. Guest

    so in other words, your new slide from k.t. is not peening at the guide rod bore but wearing unevenly there and might allow the recoil spring to once again poke out of the front....

    is that where this is going?
  7. TxCajun

    TxCajun Administrator Staff Member Supporter

    Sep 7, 2004
    I seriously doubt that, and for the record, his spring never "poked out" on the first slide.

  8. jerry-s.

    jerry-s. Guest

    i misunderstood...i thought the slide peening issues were issues because they were allowing the recoil spring to stick out of the guide rod bore. i thought the guide rod bore being worn over sized would also allow this to eventually happen.

    since this is not the case, what was the big deal with the slide peening? also what might happen with the oblong wear of the guide rod bore as he is stating is now happening?

    i personally dont mind having to buy a new guide rod every 500 or so rounds if its needed since the cost is very low, but the slide is another story of long waits for service and having to do without my gun.

  9. TxCajun

    TxCajun Administrator Staff Member Supporter

    Sep 7, 2004
    The slides peening around the guide rod hole occurred intermittently to a very small percentage of the guns built from about Aug 06 to Feb 07. It seemed to occur mostly on guns where the slide was milled thin around the guide rod hole, but since many like that did not peen, it may have also been a hardening issue. During that time, about 30,000 P3ATs were made. The number we saw in which the peening was severe enough for the springs to come though was low, in single digits. Most that "peened" showed a small ridge around the guide rod hole, and mostly that stopped after a number of rounds and resulted in no malfunction. Some folks installed the washers as an added measure. Many folks had the slides replaced under warranty even thought the guns never failed. FWIW, it is always a good idea to polish and lube the guide rod, among other things, IMO.

  10. catsize

    catsize New Member

    Aug 17, 2006
    TxCajun -- You explained that a lot more coherently than I could have -- Thanks!

    As TxCajun stated, my original slide never "failed," but it showed distinct peening that I was concerned could lead to a failure. So, I took advantage of KT's warranty and sent it in for a replacement. That's it -- I was worried, so I sent it in.

    KT replaced the slide in about a week and the gun continues to function flawlessly. Truth be told, I'm very happy with my P-3AT!

    The reason for this thread was because I observed a *very* slight elongation of the hole in the new slide. Based on JFB's explanation, above, I'm thinking that this is normal and is caused by the guide rod tilting during recoil. Since I've installed the washer - which I did prior to ever firing the gun with the new slide attached - and it fits quite tightly (it actually snapped into place) and snug against the front of the slide, not to mention being deeply recessed therein, I'm no longer concerned that the washer is causing any issue.

    Because the washer is so small, the shaping only makes about a 1mm difference in the length of the washer (at least, this would be the case in my gun). The washer in my gun is recessed deeply enough that there is at least 2mm of the original guide rod recess visible above it. Threfore, the nominal shortening of the length of the guide rod springs is about 1mm, as well. Although tolerances in firearms can be tight, in this case I don't think 1mm is going to make or break the manufactured solution.

    On a related note, JFB said that the length of the washer could cause the springs to compress too much. However, I don't know how I would determine if this was the case, since I can't see the spring during recoil. The fact that the gun is functioning perfectly leads me to believe that spring compression is not an issue, so I'm not worried about this, either.

    In short, the gun works! And, I think the washer is doing its job. Like I said above, 150 rounds without one FTA (failure to anything!).

    The slight deformation I mentioned in the OP is only visible with the guide rod removed and you have to be *looking* for it. I don't think any casual or even not-so-casual observer would see it, unless it was pointed out to them. So, I'm not going to worry about it. If anything craps out in the future, I'll just send it back to KT and let them take care of it.

    Thanks to JFB for answering my questions. I'm no gunsmith or mechanical engineer and I really appreciate the help. Although JFB may disagree with the conclusions I've drawn, above (about the 1mm making a significant difference), like I said -- The gun works better than ever. So, I'm just going to enjoy shooting it at the range and carrying it as my primary pocket piece. I'll keep an eye on it and, if anything goes wrong in the future, I'll send it back to KT and then install the washer in my new replacement slide with the recommended modifications.

    Again, thanks to everybody!
  11. TxCajun

    TxCajun Administrator Staff Member Supporter

    Sep 7, 2004
    There are a LOT of folks using those washers with ZERO reported problems to my knowlege.
  12. catsize

    catsize New Member

    Aug 17, 2006
    And, as I said above -- I'm not reporting a problem, either. I was just worried that, since I installed a little differently than recommended, *I* might have caused an issue. But, based on what I've read and experienced since installing the washer, I think everything is fine!
  13. JFB

    JFB New Member

    Jul 25, 2005
    a spring going to the maximun compression of coil to coil is not a problem.  In the case of the P3AT, It is when this occurs BEFORE the slide hits the frame.  the slide MUST go back that far[sup]*[/sup] in order to clear the extracting round and pickup the next.  when the spring goes solid before, something has to give and one or more coils will expand and the coils will jump over.

    This is easy to determine.

    put the slide on the frame without springs.  You should be able to see between the slide and the grip.  to make observation better, hold the gun up to a light so that is shines through that gap.  slowly pull the slide all the way back, while observing the gap.  You should be able to see when the end of the slide makes contact with the frame.  You must be able to see this making contact.

    Now, assemble with springs and repeat.  the hardest part will be pulling the slide back until you feel it stop while looking at the gap.  when I feel the spring go solid,

    Now If you find my original post, the numbers might be slightly different since this is now from memory :-/

    even with out the washer, I first saw a gap of 0.010" (I think that is about 0.25mm).  with my fitted washer, the gap was about 0.030" (0.75mm).  This is about the diameter of the spring wire.  so during recoil, the spring has to make its self one coil less, by that one coil going around the outside of another.  this put an observed kink in my spring  (that has not caused me any problem IF I install them same orientaion.

    The thick part of that washer is 0.063" (1.6mm).

    As I'm a consulting ME, I provide information so others man apply it as they see fit, thus I don't disagree ;)

    *. Well that aint quite true, the slide has to almost come back that far to cycle, it is just that designing and maintaining a spring thats force would reach equalibrum at exactly that point would be near impossible. I've have experimentent with adding a bufferin material to the end os the slide, and it appears to function with the slide going about 0.032" less
  14. catsize

    catsize New Member

    Aug 17, 2006
    Thanks, again, JFB! But, like I said, the gun is working better than ever, so I'm not going to screw with it!

    For the record, after 150 rounds, I cleaned the gun, which included disassembling the guide rod and springs. I did not observe any deformation of the guide rod springs (inner or outer) at all.

    So, at this point, I choose not to worry about it -- The gun works and I'm happy! Woo hoo!
  15. JFB

    JFB New Member

    Jul 25, 2005
    OH it was NEVER my intent to convence you of any thing different. I've got washer in mine

    You ask a question and I like to provide reams of useless information to justify billing so much ;D
  16. JFB...........your "uselss information" always makes my head hurt........but after reading it 3 or 4 times it begins to set in.... and I always learn a bit. So .... keep it up!
  17. catsize

    catsize New Member

    Aug 17, 2006
    JFB...........your "uselss information" always makes my head hurt........but after reading it 3 or 4 times it begins to set in.... and I always learn a bit.  So .... keep it up!

    Amazing! That's been my experience in this thread exactly!!! ;) ;D