Benefits of polishing the slide on semi auto pistol?

Discussion in 'Technical Questions & Information' started by bluesea112, Dec 14, 2007.

  1. bluesea112

    bluesea112 Active Member

    Nov 20, 2005
    West, TX
    I was looking at another firearms site today, and read a thread from a guy who was talking about polishing the slide on his 1911. This particular guy swears that it makes all the difference in the world. (That sure didn't tell me much. Now I am left to wonder what difference it makes?)
    I never really thought about polishing the slides on my semi auto pistols, but it seems to make sense. I was just wondering if any of you guys have done this?

    What are the benefits, if any?

    Thank you, in advance, for your thoughts and opinions.

  2. LDBennett

    LDBennett Well-Known Member

    Dec 20, 2003
    Hesperia, CA
    What is he polishing, the slide outside or the slide inside rails or the frame rails or ??????

    What helps for accuracy is to fit the slide to the frame. They do that typically by peening the rails on the frame closer together then lapping the slide to fit tightly into the closed up rails. Laping is not polishing. In fact the surface is dull looking when you are done but it is perfectly smooth, none the less. When done properly if you install the bare slide onto the bare frame and tip it up a few degrees (15 to 30 degrees) the slide will slowly move on the frame. Mind you not fall off but move smoothly and slowly without stopping or catching.

    Frame to slide fit is normally made with some tolerances that assure no matter the environment the slide will easily move on the frame. For original service pistols that was with mud all over the gun and rails. With todays commercial guns they have to be loose enough to assure the extremes of the tolerances between the manufactured frames and slides still allow the slide to move freely on the frame rails. If the tolerances are too tight then the rejection rate of frames and slides will be high cutting into the profit margins of the manufacturer. Tightening the rails as described above is a custom thing and allows no interchangeability of parts once done...that slide and frame must always go together.

    If polishing the rails is done poorly it can remove metal and make the slide an even looser fit to the frame. 1911's don't usually suffer from rough sliding of the slide on the rails, but can suffer too loose of a fit between the slide and frame. Polishing those surfaces might make the looseness worse.

    I suggest you not try this. But his is just my opinion and yours may differ.


  3. bluesea112

    bluesea112 Active Member

    Nov 20, 2005
    West, TX
    Thank you for the information LD. That is just what I needed to know. I definitely will not attempt it. I appreciate the details, because I would have completely ruined my slide.
  4. Seems to me, if you shoot the gun a good bit, the back and forth motion will have the same effect, sort of like mating valves to a cylinder head.
  5. Jay

    Jay Active Member

    Mar 26, 2003
    Valves are not just put into a motor, and allowed to work themselves into a mating condition. A new slide/frame combination will smooth out due to use, but the fit will become looser as time goes on. Peening causes the slide to be too small to fit the frame, and careful lapping of the slide will eventually allow the slide to do just that. .........

    s l i d e ........;)
  6. LDBennett

    LDBennett Well-Known Member

    Dec 20, 2003
    Hesperia, CA
    Interestingly, motor valve seats are cut with a cutting tool guided by a rod through the valve guide. New valves or reconditioned old ones are then lapped to the valve seat in the head. The valve job is not complete until the vavle and seat show lapped surfaces completely around the edge mating surfaces of a specified width. You never just slap in new valves and let them seat themselves! They never will and the motor will run terrible if at all.

    In the technique I suggested the rails on the frame are peened, not the slide rails but there is more than one way to "skin a cat". I think that is the way most are done as the rails on the frame are more accessible. Brownells sells hardened long strips of metal that go into the frame rails and you peen the top of the frame rails down onto those devices, closing the slot up. The Brownells kit includes several thickness and you use the one the same size as your rails of the slide. The slide then will not move on the frame so you have to lap the rails to get them to mate properly, just as in a real motor vavle job.

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