Fitting the slide and frame loose for increased reliability

[CJDOUBLETAP]

I'm getting ready to start in on my first 2011 build. My setup will be a 5" lightened slide with a bull barrel and (hopefully) a 10lbs recoil spring, shooting .40 major.

I've read quite a few posts on various forums of people saying they prefer a tighter slide to frame fit. Why? From what I've read, the general consensus is that the slide to frame fit has very little influence on the accuracy of a gun.

I personally think the "tighter gaps in the fit don't let the dirt in" theory is dumb. My experience as a toolmaker has shown me that a looser fit between mating parts will be less prone to galling and binding/sticking because of debris build up.

Right now I'm planning on fitting the slide to the frame with .0020/side clearance on all the rails. I believe this will get me a pretty loose fit without being ridiculously sloppy.

What do you guys think? Is there any benefit to a tight slide to frame fit besides a "better feel?"

 

 

[drewbeck]

I'm not a GS but I've built a few and ask a lot of questions.  From measuring a handful of guns if you're talking purely width oversized by .002 you'd still be on the tighter side of things for sure.  I true rattle can is probably closer to .010 clearances on the sides.

Vertical clearance is far more detrimental to accuracy and good lockup because the recoil spring has to have enough oomph to stand the barrel up on the lower lugs with enough force to get the slide lifted up enough to take out the vertical stacking play in the assembly.  With vertical slide its harder to get the lower lug cut right so that it is tight enough to get a consistent lockup but not so tight that it malfunctions and binds.

Keep the vertical clearance to .001 or less and you should be good.  My last slide that I had done for me was far looser laterally than I preferred and the rattle when it was clean drove me crazy but the gun grouped well at 100yds and it ran... so who am I to argue.

Most of the slide fit really boils down to perception in quality vs actually being mo betta.  

 

This is all just my observations and opinion, other who are just as correct with chime in with the exact opposite answer.  Either way, jump in and have fun, your first won't be perfect and you'll be onto the next soon enough

[fastluck13]

Tight/loose and reliable/unreliable are not necessarily related. That said, tight feels different when shooting. So tight, reliable, and accurate would be my choice.

[CJDOUBLETAP]

31 minutes ago, drewbeck said:

I'm not a GS but I've built a few and ask a lot of questions.  From measuring a handful of guns if you're talking purely width oversized by .002 you'd still be on the tighter side of things for sure.  I true rattle can is probably closer to .010 clearances on the sides.

Vertical clearance is far more detrimental to accuracy and good lockup because the recoil spring has to have enough oomph to stand the barrel up on the lower lugs with enough force to get the slide lifted up enough to take out the vertical stacking play in the assembly.  With vertical slide its harder to get the lower lug cut right so that it is tight enough to get a consistent lockup but not so tight that it malfunctions and binds.

Keep the vertical clearance to .001 or less and you should be good.  My last slide that I had done for me was far looser laterally than I preferred and the rattle when it was clean drove me crazy but the gun grouped well at 100yds and it ran... so who am I to argue.

Most of the slide fit really boils down to perception in quality vs actually being mo betta.  

 

This is all just my observations and opinion, other who are just as correct with chime in with the exact opposite answer.  Either way, jump in and have fun, your first won't be perfect and you'll be onto the next soon enough

Exactly the kind of info I was looking for. Thanks!

[drewbeck]

I reread what I wrote and I want to make sure what is said wasn't misinterpreted.  On the side to side cleaance, I was referring to, and assuming you were referring to Total Clearance and not clearance PER Side.  My reference to .010 would be total for both rails, ie .005 per side if the slide was centered.  I just wanted to make sure I didn't lead you down a path toward AK47 tolerances!

Have fun

[EEH]

If loose is OK,,why then does Les Baer,and Wilson fit thier slides and barrels so tight..

True I do have some old Colts that truly rattle when shaken side to side.

True I have custom and Baers that are tight,tight..I would fit it as tight as possible,,it will wear in.

[MrPostman]

Build it tight but not so tight that it doesn't function properly, it will loosen up/wear in after you put a bunch of rounds through it. Which you will be doing if you shoot USPSA or 3 gun

Sent from my SAMSUNG-SM-G935A using Tapatalk

[zzt]

CJ, very often the "general consensus" is wrong.  While it is true that with slide mounted sights you can have an accurate gun with a loose slide to frame fit, it doesn't always work out that way.  It depends on a number of other factors.  If one or two of them are off, your accuracy goes out the window.  Frame mount the sights and all bets are off.

Your  initial assumption that looser tolerances will make the gun run better is incorrect.  What it will do is increase wear as the slide rattles along the rails.  You should also consider that custom gunsmiths provide a tight slide to frame fit and their guns run 100%.   

[CJDOUBLETAP]

Do big name gunsmiths fit their guns tight just because the general public assumes a loose fit slide is "poor quality?"

I want to run the raw edge on my recoil springs and shoot 1000's of rounds without cleaning my gun. Isn't a loose slide going to help keep junk from building up on the rails causing the slide to slow down?

WHY are the tight fitting slides better? (Besides "that's what all my custom guns are.")

[drewbeck]

Not trying to argue with anyone above but how "tight" is tight to you?  What exactly does "tight" mean dimensionally?

Unless you have rail, can, or groove micrometers and have the ability to actually measure an exact tolerance dimension that results in the feeling of "tight" you really have no way of knowing what "tight" means.

My point is that not very many people have the tools and ability to measure the feeling of “tight” and put an actual dimension to it.  Also, without an accurate measurement of all the interacting dimensions, something may feel tighter or looser than it is.  If the slide or frame is not exactly parallel, the gun will feel tigher or looser than it actually is.

 

An easy way to see this is to pull your slide off a 2011 and look at the areas that are wearing on the underside of the slide rails.  Is the wear/polished area EXACTLY the same on both sides?  In most guns this will be slightly different.  If it’s wearing slightly different it’s because the bearing points are slightly different which means something is slightly out of parallel.  The gun may feel really tight and smooth but in reality there could be .002 width variation/tolerance in the actual dimension and the person can simply not feel or perceive this difference.

 

The feeling of “tight” is very subjective… accuracy in measuring and understanding of the measurements that typically correspond to the feeling of “tight” is not.

[CJDOUBLETAP]

17 minutes ago, drewbeck said:

Not trying to argue with anyone above but how "tight" is tight to you?  What exactly does "tight" mean dimensionally?

Unless you have rail, can, or groove micrometers and have the ability to actually measure an exact tolerance dimension that results in the feeling of "tight" you really have no way of knowing what "tight" means.

My point is that not very many people have the tools and ability to measure the feeling of “tight” and put an actual dimension to it.  Also, without an accurate measurement of all the interacting dimensions, something may feel tighter or looser than it is.  If the slide or frame is not exactly parallel, the gun will feel tigher or looser than it actually is.

 

 

 

An easy way to see this is to pull your slide off a 2011 and look at the areas that are wearing on the underside of the slide rails.  Is the wear/polished area EXACTLY the same on both sides?  In most guns this will be slightly different.  If it’s wearing slightly different it’s because the bearing points are slightly different which means something is slightly out of parallel.  The gun may feel really tight and smooth but in reality there could be .002 width variation/tolerance in the actual dimension and the person can simply not feel or perceive this difference.

 

 

 

The feeling of “tight” is very subjective… accuracy in measuring and understanding of the measurements that typically correspond to the feeling of “tight” is not.

 

I agree.

I believe I will be able to measure everything within .0002 using gage blocks, gage pins, a surface plate, .00005 dial test indicator, and a micrometer. I think I will be able to fixture the slide and frame parallel and square within .0002 across the entire length of the rails. I plan to use a surface grinder to do the machining.

I would consider a tight fit on a slide about .0005 clearance/side on the rails. But I believe that a fit that tight could jeopardize reliability when the gun heats up and gets dirty.

I have zero experience building 1911 style pistols. These numbers are just my opinion based on my tool making experience.

[drewbeck]

1 hour ago, CJDOUBLETAP said:

I agree.

I believe I will be able to measure everything within .0002 using gage blocks, gage pins, a surface plate, .00005 dial test indicator, and a micrometer. I think I will be able to fixture the slide and frame parallel and square within .0002 across the entire length of the rails. I plan to use a surface grinder to do the machining.

I would consider a tight fit on a slide about .0005 clearance/side on the rails. But I believe that a fit that tight could jeopardize reliability when the gun heats up and gets dirty.

I have zero experience building 1911 style pistols. These numbers are just my opinion based on my tool making experience.

Based on that response, I would say your ability to measure and get a handle on how the parts are going to interact is far better than 95% of the custom gunsmiths.  I believe there are only a small handful of 1911 platform builders that spend the time or take it to that level of accuracy or precision in measuring or fitting.   There are also very few that use a surface grinder due to the time it takes and cost for fixtures and wheels.  What this really boils down to is that gunsmiths cater to the market, and there isn’t a big enough demand or realized gain in performance to spend that much effort and not get a return in that investment.

 

Have you measured your slide and frame?  If not, I think you’ll be fairly surprised at what that uncovers for you.  Beneath that sandblast you’ll probably find some awesome tool marks and variation that will make a tool maker laugh.  From your perspective and level of precision, most custom gunsmiths are rough carpenters and artists.  They know how and where to fudge and push the tolerances that come from different parts and different manufacturers.  SVI is probably the only one that is truly responsible and accountable for how the frame and slide are produced.  Everyone else just figures out how to make the parts work together.

 

So now with a better understanding of how you’re going to attack this thing. I’d say if you’re going to true up the frame rails, deck and slide and know for sure that everything is parallel and true, you’d be better served making it tighter than looser.  I think <.001 vertical and .002 total width will feel tight but give you plenty of clearance and allow the gun to run as you’d like.

 

Also measure the breech face and sides and true this area up.  Most of the time the sides aren’t true and this equates to most GS cutting the hood narrower than what would be ideal so that it has clearance as the hood moves up and down during lockup so it doesn’t bind or wedge in the narrowest area of the slide.

 

FYI to all, I’m not trying to downplay the skills of the custom gunsmith in the above.  All I’m trying to do is put perspective on the level of accuracy we’re talking about.  It’s no different than hiring a cabinet maker to frame your house.  He’d have more skill and ability than is needed to frame a house to the required level of tolerance for a quality product.  But you better hope you’re not paying him by the hour to work at the same level of precision needed in cabinets as he’d lose his mind trying to true and straighten every stud and joist and it would cost a fortune without any real benefit.

[zzt]

cj, if you can fit the slide that tightly, you will end up with a more accurate pistol and it will stay cleaner.  A looser fit allows stuff to build up and cake on.  My latest build has 0.0005" clearances each side and runs like a top.  The action is buttery smooth.  When I clean it, all I have to do is rub the rails and everything comes right off.  I use it for action shooting and it sounds like a machine gun.  No problems of any kind.  The last match I shot was a 2x4 shoot.  You throw as much leaad down range as quickly as possible, because the first person to cut the 2x4 in half wins.  Again, no problems.  No failure to feed.  No anything except perfect function.

I'll say again, your premise is wrong.  Any propensity for mechanical or function problems with a properly fit tight slide exists only in your head.  That being said, go ahead and put 0.005" slop on each side.  You'll learn the hard way.

[teros135]

A question for the really knowledgeable guys - when the slide/frame is fitted properly, should the bottom of the slide touch or ride on the top of the frame (ever?), or should it travel only on the frame rails and the slide railways?  If there's a gap there, how much (or little) should it be? 

[RPatton]

I've seen 2011s and 1911s with slide to frame fits that were so close you could not feel play vertically or horizontally. Even after thousands of rounds they are still "tight" and as close to 100% reliable as possible for anything mechanical can be, even when dirty.

If it rattles like a box of rocks when new, it will beat itself into a larger box of rocks sooner rather than later.

Just my $.02.

[zzt]

Terros, the old gunsmithing manuals told you to fit a new NM 1911 so the slide rode on the rails and there was a slight clearance at the bottom of the slide.  Many modern 1911s are cut so the slide rides on the bottom of the slide.  STI is an example.  JEM Guns is another.  You will have a world of problems if you try to get the slide to run on the deck.  I have 1911s that go both ways.  I don't know if either method is better.  They both work.  My 2011 Open gun also rides on the bottom of the slide. It is tight as a drum.

About the only advantage I see with riding on the bottom of the slide is with 2011 wide frames.  You just get more bearing surface.

[teros135]

Gotcha.  Thanks.

[drewbeck]

50 minutes ago, zzt said:

Terros, the old gunsmithing manuals told you to fit a new NM 1911 so the slide rode on the rails and there was a slight clearance at the bottom of the slide.  Many modern 1911s are cut so the slide rides on the bottom of the slide.  STI is an example.  JEM Guns is another.  You will have a world of problems if you try to get the slide to run on the deck.  I have 1911s that go both ways.  I don't know if either method is better.  They both work.  My 2011 Open gun also rides on the bottom of the slide. It is tight as a drum.

About the only advantage I see with riding on the bottom of the slide is with 2011 wide frames.  You just get more bearing surface.

On 2011 slide riding on the bottom, do you clearance cut with the frame in front of the rails or the slide in front of the slide stop (about) for additional clearance during recoil?

Also curious if you know if caspian tapers the slide rails width so they get wider starting at about the front of the ejection port?  My current slide width grows (.005) in a consistent taper on the inside but the outside remains the same width.

Ive heard this is done on purpose for added clearance as the slide recoils, which to me makes logical sense but I don't know if that's true.  I didn't spend the time to confirm that the taper is consistent or equal on both sides but it appears to be.

This resulted a slide that is tight at lockup but when all the way back it has .005 ish slop in it.

curious on your thoughts, thanks

 

 

[ltdmstr]

3 hours ago, drewbeck said:

On 2011 slide riding on the bottom, do you clearance cut with the frame in front of the rails or the slide in front of the slide stop (about) for additional clearance during recoil?

That's how I learned to do it.  And I think it's good practice.  But not everyone does it.

[zzt]

drewbeck, on long 2011 and 1911 frames I relieve the dust cover for clearance.

Regarding your Caspian slide question:  if I understand your question correctly, no, I don't think Caspian did that on purpose.  I have a new Caspian slide coming in a week or two.  If it arrives in the condition you describe, it's going back for replacement.

Even a tightly fit slide will have a little wiggle in it when all the way back, because there is so little engagement, and you have to have some tolerances.  I once ordered a semi-custom 1911 with two top ends.  The primary fit perfectly, but the second one was loose.  That slide eventually wore in the manner you describe, but not as badly.

[drewbeck]

Thanks for the info above, much appreciated.

Also, just to clarify my question.  I'm talking about the groove in the slide ( that mates with the frame rails) this groove gets deeper by .002 on each side starting at the ejection port to the guide tunnel.  I'm guessing this is cut with a keyseat cutter and I don't know why it would be consistent on both sides if they cut them both in the same setup unless, A) They did it on pupose, or B - they over clamped and squeezed the slide together while cutting and it rebounded back to normal slide width after milling.

Seems like the latter is probably more realistic now that I'm thinking about it.

[zzt]

drewbeck, I took a different meaning from your Caspian question.  You said slide rails.  You meant slide ways.  On a 2011, or at least any that I have seen, the slide rails run in the frame ways.  That is, the bottom of the slide runs on the frame and the rail itself runs in the ways, bounded by the inside of the frame ways and the bottom of the frame rails.  Having the slide ways taper from front to back by .002" doesn't matter.  The ways aren't actually doing anything except providing a clearance channel for the frame rails.  Even so, it would be nice to have them parallel.

On a NM fit frame and slide, it does matter, because it is the frame rails that ride in the slide ways. In that case, if the slide ways are not parallel, there are problems.  BTW, the NM gunsmiths did it that way so that if the slide to frame fit ever loosened up you could peen the frame rails down to tighten the gun up.  That would then require the slide rails to run in the frame ways.

[drewbeck]

Thanks for the information.  I knew they were the ways, I was just totally drawing a blank for the terminology when writing the post.  This is super helpful and appreciated.

OP - Sorry if this turned into a hijack, hopefully you'll find the info useful in your build.

[CJDOUBLETAP]

Keep it coming. Good Stuff.

[CHA-LEE]

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.