Fitting the slide and frame loose for increased reliability

[drewbeck]

I think this is somewhat of a trick question given the use case of a pistol used in practical shooting events. I have had super tight and super loose guns and observed zero difference in reliability or accuracy. Every one of my guns has needed some level of fiddling or tuning to maximize the accuracy when first setting them up. Regardleas of fit tightness they all can be shot several thousand rounds between cleans or needing more lube. 

When something fails more often than not a slide will crack or a barrel will get the rifling shot out. Or I will simply change my mind on the setup and swap parts (slides/barrels) as needed to change the feel of the gun while shooting. 

I respect my guns and strive to keep them in peak functional order. But I also fully understand that they are just a tool that is really no different than a hammer. 

The reality is that regardless of fit tightness there are not many shooters that will actually shoot the gun enough to notice any difference in the long run. If you are shooting 25-30k a year then you are spending more in ammo than a custom 2011 would cost anyway. At that point does it really matter how long a single gun lasts? The reality is that an annual ammo consumption rate of 25-30k the gun it's self starts to become the cheapest part of the equation. If a single gun lasts a whole shooting season for me I consider it to have served its purpose. 

How many guns have you had that "served their purpose"? Hehe you seem to break em way before they ever wear out.

Seriously though have any of your 2011 worn out before something had catastrophic failure? It seems like most times something major just fails in lieu of actually wearing out, this further confirms that tightness is kind of moot


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[MrPostman]

I guess the real question is do you think you may eventually sell the gun? Maybe you just decide it isn't for you or another reason. Because if you do it may be hard to find a buyer willing to spend 2K on a gun with a bunch of wiggle room in the slide to frame department. Most people equate a good no slop feeling slide to frame fit as a well built gun. Just something to think about if you like to wheel and deal like me.

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[CHA-LEE]

Over the years I have shot out 2 barrels, cracked 3 frames and I have lost count of how many slides I have swapped due to cracking or changing weights with different slide cuts to test things out. 

I keep rebuilding my blasters as they fail so unless the frame fails I just keep resurrecting them.

That being said I have probably used and replaced more barrels and slides than most shooters simply because I like to test things out to see what works best. Verses sticking with the same setup for a very long time. 

You don't know which hammer works best until you test out all of the different hammers. 

In my current stable I have 3 limited blasters that all have varying degrees of "tightness". They all produce the same level of accuracy. One is so loose that I can make it rattle easily when shaking it around. Another is what I would consider tight with very little slide to frame movement. They all shoot and function the same to me with the same "dirtiness" resistance. 

Edited December 10, 2016 by CHA-LEE

[drewbeck]

It takes more than a little while to wear out a rotation of three blasters.... 

i still think you you should keep the parts and cobble together a dedicated dry fire gun.  

I'm pretty sure a 4th matching 2011 dedicated dry fire gun = boss status hehe

[CJDOUBLETAP]

Alright, time to revive this thread now that I have my slide and frame fit up. I started with a CK arms LDC Widebody frame and a bald STI unique 40 S&W slide. Please keep in mind I have zero experience building 1911/2011's, so my terminology could be a little wack.. Hopefully these pictures don't make this a page long post..

First off, I'm going to use this image to reference the measurements in which I was working off.

I threw away the note I had all my exact measurements on once I finished fitting this up. (Wish I would have saved them for this post.)

 

 

This picture was my roughest measurement, since I was going purely off the feel of the gage block fit. I used two .0920 dia. gage pins and a .5720 gage block stack to measure this. It was a tight slip fit, so I assumed there was an extra .0001-.0002 clearance between the gage blocks and pins.

I was pretty bummed that there was already .008ish (rough measurement) clearance between the slide and frame on the "C" dimension and .0005-.0020 (not perfect form) clearance on the "D" dimension before I did any machining.  That left me no chance to give the slide and frame an ideal vertical fit. I was pretty surprised about the amount of clearance on the "C" dimension, since a lot of the YouTube videos I've watched involved machining the top of the rails on the frame. The "A" dimension already was clearanced, which was fine with me because the "B" dimension had .006 of interference I could work with to fit the side to side play.

After measuring the A-D dimensions on my slide and frame using gage blocks, gage pins, a .00005 dial test indicator, a micrometer, and a surface plate I was able to start machining. (I obviously used my calipers to ball park all the numbers before I moved on to the precise stuff..)

I played around with the clamps on my grinding fixture to get the bottom rail surface that runs the length of the frame indicated within .0002 parallel with the bottom of my fixture. I placed my fixture on a sine plate and adjusted the angle on the sine plate until I was able to indicate within .0001 across the 2 inch gage pin in the slide stop pin hole. I figured I'd try to keep everything square to slide stop hole, since that part of the frame has the most influence on the barrel lockup. (I think..)

Once I had everything set up square to the slide stop pin and the bottom rail, I indicated the top part of the frame where the ejector sits out to the front rails. It was only .0016 out of form from the lowest spot to the highest spot. That's pretty decent in my opinion for a drilled hole and multiple milling setups..

I dusted this top surface flat and square removing minimal material. At this point I figured .008 clearance with out of square form was worse than .0096 clearance with good form on the "C" dimension..

Once I had the top surface squared to the bottom rail and the slide stop pin hole I was able to place that surface against another squaring fixture to work on the "B" dimension. I tapped the frame on the magnetic squaring fixture to indicate within .0001 across the .2010 dia. gage pin in the slide stop hole (pin was a slip fit). When I flipped the squaring fixture 90 degrees, I checked the rails to see how far out they were before I touched off on the grinder. I was upset that when the pin was indicating straight, the rails were about .0070 out from the back to front of the frame. There was only .006 interference before I started (.003/side) so clearly I was not able to machine the length of the rails on the sides of the frame square with the slide stop pin. I indicated the rails on my fixture .0025 out of flat in favor of the direction of squareness to the slide stop pin. Still WAY out of square compared to what I was hoping for, but that was as good as I could get it while still being able to clean up the entire surface on the grinder. Confused yet??

I ground equal amounts off each of the side rails keeping them parallel with each other and square to the top of the frame, which I squared to the slide stop pin and bottom rails earlier. I ground the "B" dimension on the frame to the exact number I got for the "B" measurement on the slide. I was barely able to start the slide on the frame. (Approx. .5-.75 inches.) I debated grinding the frame further to the fit I wanted, but decided to lap it the rest of the way. My decision was based on the blasted finish on the slide. I knew it would wear quickly, so I wanted to lap it smooth to help preserve my ideal fit.

The lapping compound I chose should have given me about .0002-.0003/side clearance. (I didn't measure.) I had to lightly tap the slide back and forth a couple dozen times before I was able to cycle it completely back and forth using only my hands. I cleaned lap off and the slide will slowly slide off the frame without any influence if I tip the rails perpendicular with the ground and give the frame a shake.

This is as tight and smooth as I could have possibly fit this slide and still have it move free. I personally think the fit is too tight and the gun will not function once it heats up and gets dirty. I figured It is a piece of cake to loosen it up if it has reliability issues because of the fit. The perfectionist in me wants to try a different frame with some more stock so I can also fit the vertical play and completely square the rails with the slide stop pin hole. Do you guys think I'm wasting my time putting more work into this frame since there is so much vertical play?

Edited January 22, 2017 by CJDOUBLETAP

[ltdmstr]

Two or three tenths is pretty darn tight.  I would probably lap a bit more to get at least 1/2 thou clearance, but if you want, you can leave as is and see if it functions when the rest of the parts are fit.  Keep in mind you're going to have the barrel locking up solid when that's added to the equation.  So nothing is going to move when the gun in in battery, which is really what's important.  Regarding the C dimension, it's not normal or necessary to have it fit there.  And I don't know who posted videos saying to remove material from the top of the frame, but that shouldn't be necessary and is typically not something you want to do.  

Edited January 22, 2017 by ltdmstr

[drewbeck]

Being able to consistently do what you just did is beyond the skill set & tooling capabilities of many accomplished gunsmiths.  I'd say it's a waste of time to try to make that frame fit something else any better, finish that gun and you'll uncover more knowledge as you fit each piece into the system.

 

if you want to purely try making one "perfect" just to see if you can ( which I totally understand the thought process) I would start with an 80% frame and cut it yourself so you don't have to fix an issue to begin with.

 

out of curiosity, how long did it take to measure, cut, and fit this slide? And more importantly how long would it take to do them now that you've done it?  I think this answer will explain why it isn't done for today's typical custom gun price point 

[ltdmstr]

I should have also mentioned in my post that fitting at only the B and D dimensions is the norm.  Not sure why that is, but it does simplify things since you only have to remove material from the sides of the frame and bottom of the slide.  That might not be ideal in terms of design aspects, but most people don't have the equipment or skill set to machine some of the other areas.  Plus, fitting all of the surfaces would add quite a bit of time and effort to the job, which is really beyond what's needed for the application.  As CHA-LEE stated in his post, accuracy is not really dependent on a tight slide and frame fit.  The key is how well the barrel locks up, and how consist the lockup is relative to the other parts (mainly the sights).  Btw, nice to see someone doing this work on a surface grinder rather than a mill. 

[theWacoKid]

Parts are going to come with the C dimension clearanced.  I haven't seen any 2011's fit there.  B and D are the typical dimensions to fit and provide bearing surfaces.  It does suck that the D dimension did not come out with enough interference to really "fit" and is likely an occurrence from mixing different makes of frame and slide.  Still should be no real problem.  Work looks good.

[CJDOUBLETAP]

5 hours ago, drewbeck said:

Being able to consistently do what you just did is beyond the skill set & tooling capabilities of many accomplished gunsmiths.  I'd say it's a waste of time to try to make that frame fit something else any better, finish that gun and you'll uncover more knowledge as you fit each piece into the system.

 

if you want to purely try making one "perfect" just to see if you can ( which I totally understand the thought process) I would start with an 80% frame and cut it yourself so you don't have to fix an issue to begin with.

 

out of curiosity, how long did it take to measure, cut, and fit this slide? And more importantly how long would it take to do them now that you've done it?  I think this answer will explain why it isn't done for today's typical custom gun price point 

Took me 4 hours from start to finish taking all the measurements and getting the slide fit on. Probably would have taken another hour to fit the "D" dimension. I think the "D" dimension would be WAY quicker to do than the "C."  The slide would be a lot easier to hold onto and indicate square than the awkward shape of the frame.   

If I did it again the same way I think I could do it in about 2.5hours. If I just milled the rails parallel with the outside of the frame and lapped the slide on, like most of the videos I've watched, I think I could do it in under an hour pretty easily.

[CJDOUBLETAP]

3 hours ago, theWacoKid said:

Parts are going to come with the C dimension clearanced.  I haven't seen any 2011's fit there.  B and D are the typical dimensions to fit and provide bearing surfaces.  It does suck that the D dimension did not come out with enough interference to really "fit" and is likely an occurrence from mixing different makes of frame and slide.  Still should be no real problem.  Work looks good.

Good to know. Thanks.

[CJDOUBLETAP]

7 hours ago, ltdmstr said:

Two or three tenths is pretty darn tight.  I would probably lap a bit more to get at least 1/2 thou clearance, but if you want, you can leave as is and see if it functions when the rest of the parts are fit.  Keep in mind you're going to have the barrel locking up solid when that's added to the equation.  So nothing is going to move when the gun in in battery, which is really what's important.  Regarding the C dimension, it's not normal or necessary to have it fit there.  And I don't know who posted videos saying to remove material from the top of the frame, but that shouldn't be necessary and is typically not something you want to do.  

Yep, I think if there was any less clearance I wouldn't be able to get the slide to move free. I'll probably end up loosening it up a bit, but I'm going to test fire it first once I finish everything up just to see what happens. Might be able to really figure out if a tight slide frame fit really is just as reliable as a loose one..

[CJDOUBLETAP]

I still think a loose fitting slide (.003-.005/side clearance) with perfect squareness and ground/lapped surface finish will be the more reliable than a tight fitting slide. I looked through all the old posts in this thread and it seems like the majority of people think tight is better. Nobody seems to have a good reason why though..

I think the "a loose slide will wear out faster" theory is stupid. The increase in wear over what a tightly fit slide would get has to be extremely minimal, if any. I just can't see how this makes sense..

I'm starting to think the big name gunsmiths fit their work tight just because people that don't know what they are talking about assume a tight fit means better quality and accuracy. There are a few replies to this thread of people with loose guns that are tack drivers.. Am I just a stubborn conspiracy theorist? 

Its killing me not really knowing what the ideal fit is. Someone has had to have tested this before, right? I just want to build the perfect gun...

[drewbeck]

Thanks for the info on the amount of time it took you, 

just remember you haven't achieved any level of accuracy until that barrel is fit.  Not the least bit worried you'll have issue but that is more important than the slide

[drewbeck]

I think you'll not find any dispute in anyone saying the "ideal" fit is everything to do with lockup and less about slide fit.  

 

Maybe that hat answers the question, the only thing everyone agrees with is that lockup is the only thing that matters

[ltdmstr]

True on the lockup being the key factor.  As for slide to frame fit, there's no real downside to a tight fit if it doesn't affect reliability.  Most of my guns are extremely tight when new, but after a few hundred rounds for break-in, they're 100% reliable and smooth to the point that you can hand rack the slide on a full magazine and barely feel the round going into the chamber.  That's what I'm after.

[theWacoKid]

22 hours ago, CJDOUBLETAP said:

I'm starting to think the big name gunsmiths fit their work tight just because people that don't know what they are talking about assume a tight fit means better quality and accuracy. There are a few replies to this thread of people with loose guns that are tack drivers.. Am I just a stubborn conspiracy theorist? 

Atlas is a pretty respected gun builder. He has a video discussing slide fit and admits to building guns tight because for whatever reason people associate that with quality. He says he fits slides on his own guns looser. He agrees lock up is more important. 

If the gun is accurate I don't care about the slide. Although I admit I like the feel of a tight slide that glides. Also there's probably some merit to tight slides and consistenct lockup for max accuracy in guns with frame mounted optics. But still I have two open guns with 'loose' slides that are plenty accurate. 

 

[762rocstarr]

Any updates or progress report? Dibs on shooting this blaster once finished! 

[assaulter]

How did it turn out?  Starting a 2011 soon myself.