View Full Version : Fitting slide to frame where too tight

March 4, 2009, 02:10 PM
So I've still got the 10mm Auto Ord kit that I don't want to shoot on my 1911. I talked a while ago about doing a build with it, basically just getting a frame to build up and then slap this sucker on board for a dedicated 10mm. Got the frame and have been moving slowly on picking up other parts. Finally got around to taking a look at everything last night and indeed, it seems the slide will need a bit of work to fit to the frame. Whether the slide is too narrow or the frame is too loose, I'm not sure, but I figured I would bring it up here to see how people thought I should proceed. I've done a little bit of searching into how to fit the two, but there actually aren't a bunch of threads on the topic as I expected. So I guess I'd ask for input and the methods best for a beginner.

What sounds easiest, that I've read so far, is basically rubbing it down with some lapping compound and then pounding it back and forth with a hammer until it's doable by hand, then gradually improving it with other substances until it will slide under its own weight. If anyone can recommend specific products or techniques for this method, or has a better method for my purposes, I'd appreciate it.

Below are some pictures of what I'm working with. No particular method to selecting the angles other than they were the ones that were in better focus :)





March 4, 2009, 02:11 PM




March 4, 2009, 02:27 PM
Will they go together at all? Move at all? I would be reluctant to start pounding. I would use a vise to tighten/narrow the slide rails a bit. I have heard of a method where you can coat the rails with a rubbing compound of sorts and simply go to town racking it. The compound ends up rubbing down the high spots and you are left with a solid, custom fit.

March 4, 2009, 02:51 PM
Ah yes, I forgot to mention - this is as far as it will go by hand. I mean, I didn't really crank on it, but I figured I'd ask before I start doing anything that will begin deforming metal.

March 4, 2009, 02:57 PM
If I was being adventurous, I would put a piece of 400 grit wet/dry paper on a class surface and slide to rails of the slide back and forth on it a bit to make sure they are uniform. :)

Also make sure there are no burrs or anything inside the slide.

Brian Pfleuger
March 4, 2009, 03:03 PM
Can you tell which areas are too tight? Obviously, if you sand areas that already clearing enough then it won't help you. I almost think I'd get it down enough so that it goes together and then perhaps leave some lapping compound on the rails and then cycle it by shooting until it's reliable. That seems like it would make the most perfect fit. I could be crazy on that idea, don't know.

March 4, 2009, 03:04 PM
I used lapping compound to fit a 2nd Colt slide to my Mark IV. The key is to
use minimum amounts, the smallest amount to do the job. I used a toothpick.
I would also try using a darkening substance to find the high spots.

March 5, 2009, 08:39 AM
I know we've got some 1911 smiths around here - anyone got anything else? I agree that I should probably not just take down the slide and start whacking with a mallet, but I don't want to use a stone or bend the frame rails unless I've got some good input.

March 5, 2009, 09:24 AM
First thing you need to do is measure the slide and frame and write down the dimensions. Removing material from the frame is 1000x easier than the slide. If it were me and it isn’t I wouldn’t try to narrow the slide rails with a vise…takes A LOT of feel to do it and the line from a good slide to a cracked paper weight is VERY FINE. Get some good quality files (smooth, 2nd cut and bastard), some stones, water soluble grinding compound, Dykem and a lead hammer if you can find one. Start with the file…depending upon how much material needs to remove start with the bastard file make a couple passes (no more than 5) then try the slide…LITTLE at a time. At some point you‘ll want to go to the 2nd cut file…same thing couple passes try the slide. It’s hard to say how many passes your need with the files; it depends on how hard you’re pressing and how good it’s cutting; 99.8% of slide fitting is feel.

March 5, 2009, 12:15 PM
Get a bottle of Dykem and put some on the frame rails and find out where the parts are binding. As GE-Minigun said, it is much easier to take material off the soft frame than the heat-treated slide, but that doen not mean that is where it needs to be removed. Fitting is not just filing away until things are no longer too tight.

Bill DeShivs
March 5, 2009, 02:03 PM
You can use black Magic Marker to see high spots. WD 40 takes the marker off.

March 5, 2009, 02:42 PM
Prussian Blue used very judiciously may be more helpful that the Dykem or magic marker. First I'd work on the frame, not the slide and would not squeeze anything in a vise... likely to make things worse or even unsalvageable. If you have a good straight edge, you could start by checking to see if the top and outboard edges of the frame are bowed. If you find a problem there, stoning would be preferable to sanding, but if you do sand, wrap the paper around a flat block first and sand a little, check a lot. If the problem is on the rather in-accessible surfaces of the frame, or if the slide is the problem, it's going to be harder to work with and getting someone to analyze the mating surfaces and fix the problem properly by precisely machining the offending surfaces might be the best course of action.

I could be wrong and maybe pounding the slide back and forth with lapping compound is how it's done, but I wouldn't want to treat my gun that way. :(

March 5, 2009, 03:00 PM
I think that you've got to take some measurements before doing anything. Don't just go banging and squeezing things without knowing what needs to be done, and by how much.

Hunter Customs
March 6, 2009, 09:08 AM
As already stated, the first thing you need is measurements to go by.
Then I would remove the ejector from the frame.
Then mill the frame rails to a close friction fit to the slide, using a mill should true the rails unless you have some really low spots in the rails. Also using the mill will allow you more control over the amount of metal removed.
Finish lap the frame and slide together with 1200 grit lapping compound, when completed the slide will feel as though it's sliding on ball bearings.
The slide should move fore and aft on the frame by it's own weight.
I advise you to not pound the slide on the frame as you can cause stress cracks in the muzzle end of the slide.
Bob Hunter

March 6, 2009, 10:05 AM
I should go back and point out that depending on what the actual problem is, squeezing the frame in a vise could work. I've straightened many an item with a vise. Problem is, one needs a good vise, like a machine vise, with properly configured jaws. Then one needs pusher blocks of various lengths, a few indicators, a very light touch and lots and lots of patience.

I'd mill it.

March 6, 2009, 04:58 PM
why would you squeeze a slide thats already to tight and binding?just wondering?
i would l;ook really close to assure there are no small burs on the frame or slide .
ive had exact problem before and once it broke free of the bur it was butter.