P238 ramp

P238 ramp

This is a discussion on P238 ramp within the Defensive Carry Guns forums, part of the Defensive Carry Discussions category; I was cleaning my p238 and noticed what I guess you would call tooling marks. Now that the black finish is wearing off it is ...

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Thread: P238 ramp

  1. #1
    Member Array Joonbi's Avatar
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    P238 ramp

    I was cleaning my p238 and noticed what I guess you would call tooling marks. Now that the black finish is wearing off it is very obvious. You can feel them easily. Is this normal for sig. So far it has been very reliable but thinking about polishing the ramp. Has anyone else noticed this? For $600 you wouldn't expect this. The gun is great so far though.


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    IMO, a feeding ramp needs to be polished only when it causes an issue. Machining marks themselves may or may not cause a problem. An improperly performed polishing is more likely to cause problems than solve them. Unless your gun develops a feeding problem, I'd leave well enough alone. My S&W 3rd Gen has a few marks on the ramp but has never failed to feed a round.
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    VIP Member Array Kilowatt3's Avatar
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    I'm not real familiar with the P238, but it's entirely possible that the "texturing" is deliberate. Contrary to a widely-held misconception, a glass-smooth metal surface has more friction than a properly textured (e.g. honed) surface. Guys who polish their feed ramps to a mirror finish are generally doing more harm than good.

    I'll pull my Sigs out and see what their ramps look like.
    Regards,
    Jim
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    Quote Originally Posted by Kilowatt3 View Post
    I'm not real familiar with the P238, but it's entirely possible that the "texturing" is deliberate. Contrary to a widely-held misconception, a glass-smooth metal surface has more friction than a properly textured (e.g. honed) surface. Guys who polish their feed ramps to a mirror finish are generally doing more harm than good.
    I think the tribologists I deal with would argue that point. Care to 'splain it a bit?
    Smitty
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    VIP Member Array Easy8's Avatar
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    I agree, polishing a ramp cannot hurt it unless you remove so much metal an deepin the ramp itself but its hard to do unless you use a dremel or something. Very fine emery cloth an some brasso does a nice job. I usually stuff some cotton in the barrel to keep any gunk from getting inside.

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    Member Array Joonbi's Avatar
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    Well I decided to do it. I used 600 gently and carefully then spent about 4hrs with 2000 grit. All by hand. Fired 100 ends and worked flawlessly. Mirror finish. I was especially careful to not remove anything except the marks.

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    VIP Member Array Kilowatt3's Avatar
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    Quote Originally Posted by gasmitty View Post
    I think the tribologists I deal with would argue that point. Care to 'splain it a bit?
    You might ask them! If your tribologist colleagues are well-versed in the metallurgy and physics involved, they won't argue it. Your garden-variety shade-tree tribologist might.

    There are two main things that contribute to the increased friction between extremely smooth surfaces:

    At the atomic level, friction is caused by attractive (electromagnetic) forces between atoms. These forces follow the inverse square law, so that they diminish very rapidly with distance. If you look at an electron photomicrograph of a typical metal surface, it looks like a mountain range. Two normal surfaces in contact with each other only actually "touch" at the peaks of the irregularities; the majority of the atoms are held away from each other, reducing the attractive forces between them, and therefore the friction. If you shave off all the peaks, you've got a whole lot more atoms in very close proximity to each other, increasing the forces.

    The extreme example of this is if you have two surfaces that are "perfectly" (i.e. atomically) smooth and perfectly clean, in a vacuum they will actually weld to each other without any heat being applied. This doesn't happen "in real life" because a) contaminants and air between the surfaces interfere with the process and, b) we can't normally get a surface polished THAT smooth. The forces are at work, though, and friction is increased on an extremely smooth-polished surface.

    The second factor is a lot simpler. A slightly textured surface retains a layer of lubricant a lot better than a glass-smooth surface.

    A good real-life example of the smoother-is-not-necessarily-better principle is in a piston engine. Ask any expert mechanic what happens if you polish the cylinder bore of a high-performance engine to a mirror finish. The engine will often seize up within minutes, if not seconds. This is a very common mistake among aspiring young mechanics! Instead, the cylinders should be stress-honed to provide minimum friction AND to better retain a layer of oil on the surface.

    Hope this helps. Let us know what your tribologists have to say!
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    Jim
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    The second factor is a lot simpler. A slightly textured surface retains a layer of lubricant a lot better than a glass-smooth surface.
    This is what the smart guys at my jet engine division, particularly the high-speed bearing guys, go with.

    Practically speaking, I doubt that the respective surface finishes on a feed ramp and a bullet could reach the levels required to actually increase friction.
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    Smitty
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    Member Array Joonbi's Avatar
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    Would surface tension play into that? If you poor water on a smooth surface,it will build unless the surface tension, then it flows very well.

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    Being a P238 aficionado I have seen cases where the feed ramp needed to be polished and cases where not. Failure to chamber is not necessary a ramp issue for example. Sig had some magazine issues some years back. In all but the most extreme cases I have found that shooting 50-200 rounds of round-nosed ammo resolved most all feed ramp issues. Now the LCP is a different story. When I got mine, (ca, 2008) The feed ramp was rough but having read a lot about the pistol, I used a Dremel tool with a 3/8" polishing cone and rouge to "polish" the feed ramp and make it look almost like glass. [Polish, clean, Polish, clean etc.] Never had a single issue.

    That being said, my general position is this; If you have the necessary stuff to do a nice polish job, why not? Remember you are not removing metal - you are simply doing a final cleanup of the finished product. The last time I did a LCP for a friend, it took me all of maybe 10 minutes.
    Diddle
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