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Fitting an STI 2011 Frame to an STI Slide


Ryan626

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Hi Guys,

So I am looking to assemble a backup 2011 gun on the cheap end. I have a friend selling me an STI Edge complete upper. I am about to order an STI frame with a ramp cut. My question is how much work would it be trying to fit this together? Does it look like I would just have to file a little material here and there? I am thinking how since both are from STI, the specs should be close and maybe not need a lit of fidding.

Any information will be greatly appreciated.

Thank you in advance.

Best Regards,

Ryan

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Unfortunately, there is enough variation in frame rails and slide ways and rails that you cannot be sure to get a frame that will work. Typically, you fit the frame to the slide, so if there is enough material on the frame rails, you are in luck.

I'm going to say typically, but take that with a couple of grains of salt. "Typically" an STI frame will have rails that are a little oversized in width, and a little undersized in height. STI slides generally have too much material on the bottom of the slide and you have to take as much as .006" off to get it to go on the frame. That will already have been done to the upper you are contemplating buying. If too much has been removed from the slide, you'll be riding on the deck.

If you want to go ahead with this, I'd suggest ordering from Brownell's or someone who will allow you to return the frame for another if it doesn't look like it will fit. That being said, I recently bought an entire top end for my Tactical Sport. It goes on loosey goosey, but it will shoot into an inch circle at 15 yards. So remember, there are lots of things more important to accuracy than slide to frame fit.

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Barrel fit is much more important as far as accuracy goes. The last few I fit needed .006 to .008 off of the bottom of the slide to get it started on the frame rails. Then the frame rails sides needed to be trimmed about .005 to .006 on each side of the gun to get a tight fit with no slop. Most likely it will fit your gun but will most likely not be as tight as a fresh fitting with new parts. The other thing is blending the back of the used slide to match the frame. It may line up well enough but it may need trimming if you want it to look good asthetically. It is easy to do new parts because you just put it together and hit it with a 120 grit sanding drum on a dremel to blend the two surfaces together. You can't do that with the used one or it will be off when you put the slide it came with back on. Now I have owned a gun that instead of trimming the frame rails they cut the channels on the slide to fit the oversized rails so even though this is not the norm it can come that way so just be aware of this. You should have the person selling it to use a dial caliper on the width of the slide channels and then you can check the width of the frame rails on your gun to get an idea if it will fit or not.

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Can you just buy the complete edge from your friend? maybe a little more than building but a lot easier

Living in the Republic of NJ, we have to apply for pistol permits for every pistol purchase and can only purchase 1 every 30 days. Applying for permits is a task itself. My friend selling me the upper gave the frame to Limcat so he can build on it so he doesnt have to apply for permits. For the price that hes asking for, hes basically giving it to me and thats where my idea came about.

Edited by Ryan626
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I'm not sure if they still offer it but STI had slide and frame kits that were fit together.

Yes they do but I believe I would have to mill the sight cuts plus fit the barrel. Knowing that this upper has a good fitted barrel already, i thought it may be easier.

I appreciate all the input! I found a frame from speed shooters and will slowly give this a shot! Found a buddy who has built a couple of 2011 that is willing to help.

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Typically, slide fitting requires removing material at C and H dimensions in the above diagram. But that's not always the case. Both slide and barrel fit can both be done with hand tools, but I would not recommend it for most people. If you give someone a square block of material and file and ask them to remove a couple of thousandths from one side, you'd be amazed with the result.

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One approach that works well is to use a small surface plate (you can get a 9x12 for cheap from Enco) or piece of heavy plate glass and some sandpaper. That way it's pretty easy to keep things square. Works a lot better than files and stones for most people.

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I'd spring for the surface plate. It is much, much flatter that a glass surface. I'd also recommend you get some adhesive backed sand paper. I have regular and adhering sheets down to 6000 grit. You will also need stones to polish the frame ways.

BTW, $25 buys you a certified surface plate that is even to within 1/10,000". That is plenty good enough for pistol work. Gesswein is a great source for stones and sand paper.

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I wouldn't be surprised if the slide fits. It has already been fit to one STI frame.

Normally, they fit the slide to the frame, not the other way around so I'd say try it. You might be pleasantly surprised.

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Only slightly off topic but can you just mill the slide to fit a frame. As in the case off having two slides for one frame.

The frame has oversized rails, so if it has already been fit to a slide then the rails have been trimmed to fit the slots in the slide, usually about .005 to .006 on each side. If you are going to fit a new slide to a used frame, then the bottom of the slide will need about .008 taken off so it will start on the rails. Best to use a mill to do this but it can be done with a surface plate with sand paper or stones.It will however take all day if you go the manual route.

Edited by MrPostman
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It takes about 10 minutes to take .006" off the bottom of the slide evenly with a good, large flat file. Most of that time is spent measuring. Then it takes about a hour with the surface plate to take off the remaining thou. You start with 220 and work your way down to 1000, making sure you apply pressure evenly. When you are done and the slide just goes on the frame, you clean the surface plate thoroughly and the slide. Rub the slide lightly sideways along the edge of the surface plate with the spring tunnel hanging over. See where it is marked. Touch those marks with a fine sanding stick. Clean and repeat. When it is dead flat, the slight marks made cover the entire bottom surfaces of the slide. Then break out the 2000 or 3000 grit paper, adhere it to the plate and make several passes. It works like a charm.

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Thanks for that! I was looking at the Everglades one but matrix is half the price. Anyway here is a pic of the slide with the new sti tactical frame. It looks like a little off on the side of the frame and it should go in.

post-29881-0-59477300-1458523364_thumb.j

Edited by Ryan626
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  • 2 weeks later...

Making sure the barrel fits correctly will be a bigger chore than the slide to frame fit. The last two STI frames I worked with were not cut correctly. Barrel bed was not deep enough and the VIS wasn't cut correctly either. All easily corrected if you have a mill and the knowledge but still a pain. Make sure the barrel is contacting the vis and not the barrel bed.

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