1911 45ACP Headspace Gauge

[Dave Sample]

The Play? "Much Ado Over Nothing' The author? William Shakespear. The New version? Can't check chamber on factory gun without headspace gauge : by 1911 Tuner.



Guess what?



Inserted in the Chamber of the factory Norinco barrel. Jose' can you see?



Guess what that is beside the Chamber Go Gauge? Is it an Empty Case?



Or Dear! It tells me the same exact thing that the Go Gauge does.



I used an empty fired case from that gun so you people who are paranoid about the way that I do things in the shop would not be scared. I have used my method for over 50 years to make sure a barrel was not defective or that some idiot had reamed it too deep with a chamber reamer. I have built guns with NM barrels for 20 years without any problem at all. As a Professional Pistolsmith I have had great success in not blowing up any guns from a gunshow, because I do not buy guns at gunshows. I have yet to have a headspace problem with any 1911 in any caliber and that includes 10mm Centaur, 400 Cor-Bon, 38 Super, 9mm, and of course, 45 ACP. I wonder why Ed Brown, Bill Wilson, Fred Kart, Irv Barstow, and other barrel makers never mention chamber check gauges? Maybe some folks read too much! None of my Pistolsmith pals use them either. I will ask them all at The Shot Show why they are so bold as to make these barrels and sell them without including these Go and No Go Gauges. I will reoprt back later and tell you what they say about this matter.

 

[1911Tuner]

Gauged

Excellent Cap'n! You're almost there! Ya still gotta add the slide to the equation though...

Now put the barrel and gauge in the slide and measure the gap between the breechface and the rear of the gauge, and you'll know what the amount of headspace there is with that barrel in that slide with a minimum gauge. It might be dead perfect, and it might not...but probably not. I like about .003-.005 inch of headspace in a carry gun as verified with the .898 GO gauge
and the hood flush. Some like less...mainly for accuracy...but I tend to go more loosey-goosey for reliability.

Then, try a NO GO. If the gun will go to battery on the NO GO, you have excessive headspace, and the condtion must be corrected before the gun is deemed serviceable.

Just eyeballin' your Christmas Nork...I'm gonna take a guess that your headspace is about...mmmmm...010-.012 inch on the GO gauge.

On second look...I'll say that the headspace on that barrel in the OEM slide is gonna hit closer to .020 inch. The feeler gauges will tell the tale, Cap'n. We're gonna make an armorer outta you yet!

 

[Bill Z]

I guess .005 might be okay for a service grade gun or factory assembled gun. I however tend to lean towards hard fit with a max runout of .003 with .003 to a max of .005 on the sides of the hood. Properly fit, there is no reliability issue that you speak of, improperly fit it wouldn't matter what you spacing is, there won't be any reliability. Your biggest issues with reliabilty at this point would be the gap at the feedramp and to wit, safety would suffer with an overly agressive throat or throat erosion. The go/no go guages won't tell you a thing about that. If the guage/round fits flush at the hood, and the hood is hard fit with a max of .003 on the outside demension, there cannot be a headspace problem. The throat could still be wrong though, and here in could lie your real problem.

 

[1911Tuner]

Hard-Fit

Yes! Now we're gettin' somewhere.

If you'll check the hood to slide gap on several factory guns, you may find that they're quite a bit looser on average. I've seen Colts run as high as .012 inch at the rear, and .005 or more on the sides. Very sloppy.
Recent Springfields are a little better, and Colt is catching on. But...
these are assembly-line drop-in barrels. As long as the guns go to battery on a GO and don't go to battery on a NO GO..they pass inspection.

For a hard-fit match-grade fit, I like zero clearance at the hood to slide fit,
.595 gauge flush with the hood plus /minus .001 inch...and a little tighter on the sides. Something on the order of .003 inch or a bit less. For a hard-fit service grade gun with accuracy in mind, I like to see the barrel hood lock vertically in the slide with just light thumb pressure. For a boondocks gun that may be neglected for a few days...the clearances mentioned previously are fine as long as vertical lockup at the rear is good and the bushing isn't
too sloppy. .001 fit to the slide bore, and .003 clearance at the barrel works well. For these, I use a .895 gauge as a GO and a .910 as a NO GO.

I also like to see that the locking lugs engage evenly on the horizontal plane...but that can get a little tedious with some slide/barrel combos.

Let's roll!

 

[Jim K]

Hi, Tuner,

"For these, I use a .598 gauge as a GO and a .910 as a NO GO."

Huh? Sure you don't mean .898 as a GO?

I think the reason few folks worry much about pistol headspace is because the fairly low pressure and the short, strong, case let the case move back rather than tearing itself apart as in a rifle. Further, either the extractor will hold the round for the firing pin or the firing pin will reach out far enough (as in the 1911) to fire the primer, so the gun will usually fire even with way excess headspace. In fact, the 1911 was designed to function with excessively short cases (equivalent to excess headspace), which is why the extractor hook is so far from the breech face.

Jim

 

[1911Tuner]

Go!

Jim said:

Huh? Sure you don't mean .898 as a GO?

ROFL!! Is my dyslexia showin'?

I meant an .895 gauge. I made one that's .003 under minimum for special applications. Lemme go fix that. The .910 is also a homemade gauge.
__________________

And:

In fact, the 1911 was designed to function with excessively short cases (equivalent to excess headspace), which is why the extractor hook is so far from the breech face.
**************

Exactly so...and as long as the excessive headspace isn't in the rearward direction...and allows the case to back up into the breechface...it'll work and be safe. On the other hand...If the chamber is cut too deep, and the hood matches it..and there's a gap between hood/cartridge rim and breechface...
the round backs up far enough to let the head bulge or blow out. I suspect that this may be part of the reason that genuine GI-spec brass is a little heavier in the head area. I've seen several barrels that held the rim flush with the hood, just like the Norinco barrel in the pictures...yet still produce bulged brass just forward of the case head. Closer checking with gauges and shim stock showed why. There was a huge gap between the rim and the slide. Dominic's Norinco barrel was an example of the condition.

Thanks for the heads up! Sometimes my knarled fingers get all tangled.

Cheers!

 

[OzarkExpedition]

I have to chime in here. I dont really care for this I know it all attitude.

I think there are several ways to do any number of things. My way may not be your way. Dave Samples way certainly isnt your way Tuner. Doesnt mean that he is wrong and it doesnt mean he owes you any explanation either. I belive that he has gone out of his way to demonstrate his skill and knowledge. He has only done this (so far as I can tell) to show people who read your posts on threads that he has started that he isnt messing around, not a mere hobbiest but a true professional.

Having said this, I believe that you are also very knowledgeable in your chosen profession. Isnt it better to sit back, listen, read or watch as another demonstrates his skill? More can be learned this way than by speaking out or having the last word.

I have heard you say that you only speak up or speak out becuase you want others to know more about what it is that is being discussed at the time. I honestly believe that before anyone here attempts something they saw in a forum post that they will investigate it further. It is a forum, and there is a topic called gunsmithing they can use for assistance along with private messages and emails.

Just my opinion.

Ken Smith

 

[Old Fuff]

Ken:

The subject under discussion is how to determine if a 1911 style pistol has excessive headspace or not. The answer is important because excessive headspace can result in a damaged gun if the locking lugs shear, or an unsupported cartridge case ruptures and blows high-pressure gas and fragments down the magazine well while badly damaging the magazine itself and possibly causing other cartridges to detonate. Obviously there is a substantial potential that the gun’s user will be injured.

Part of Tuner’s job as a moderator is to be sure that information that is posted by various individuals does not contain something that could get an inexperienced reader into trouble. He uses his own judgment in doing this, which is his right because he is a moderator. If you question his expertise feel free the use the search function and research using the keyword “Tuner.†You will find a huge body of minutely detailed information on the 1911 pistol. You will also find a considerable number of posts from various members thanking Tuner because they have followed his advise and/or instructions and found that they worked and solved problems that others haven’t been able to correct. In other cases individuals have visited him in his home and again, he has fixed guns and set them working when others tried and failed.

In this case Mr. Sample’s position on checking the headspace in a 1911 pistol is completely contrary to established industry procedure. While Sample’s method will determine the depth of a chamber it does not determine correct headspace because it ignores the fact that the barrel is positioned in the slide and locked in place by lugs on top of it that fit into matching groves in he slide. If for whatever reason there is a discrepancy between the barrel’s lugs and the slide’s grooves the barrel may shift forward when the pistol is fired, and this can cause excessive headspace while near maximum pressure remains in the barrel. Unlike a cartridge in the chamber a no-go gage being pushed by the slide returning to battery will push the barrel forward and either stop the slide from going into battery (as it should) or allow it to do so (which will indicate excessive headspace).

Tuner knows this. He also knows that what Sample advocates is potentially dangerous, and he has forcefully reacted to it, as he should.

If you would like another expert opinion outside of this forum I suggest that you obtain a copy of a book by Jerry Kuhnhausen entitled: “The Colt .45 Automatic – A Shop Manual†(Available from Brownells at www.brownells.com). It is “the†recognized gunsmithing manual on this particular handgun, and it was prepared with the full assistance of the principal manufacturer of this pistol. I think you will find it helpful in understanding this as well as many other issues that frequently come up for discussion here and elsewhere.

 

[1911Tuner]

Know it

Wow! Thanks Fuff.

Ken...It's not so much a know it all attitude as it is knowing how to determine
that a firearm has good headspace...not only for the sake of safety, but for accuracy and even functional reliability. Barrel AND slide are necessary
for this determination...even if a loaded round of unknown case length is used
as a gauge. Go and study the subject, and it'll make more sense.

 

[Wichaka]

In a lot of areas in life, there IS more than one way to skin a cat......so to speak.

But in some areas, there IS really only one way to do it...........here's one of them. Ya got have all the parts to make the determination.........or it's just a guess. And this kind of information needs to be put out right........for safety sake.

Everything I've ever read on the subject of head space on a 1911 says you've got to have the barrel & slide to make the proper determination. As Fuff said, Kuhnhausens manual was put out in conjunction with the manufacturer.........who knows better how to properly check & set up proper head space on the 1911..........Sample or Colt? :banghead:

I rest my case on this thread............

 

[Dave Sample]

Better to be thought a fool and remain silent, than to open your mouth and remove all doubt.

Fired cases from this barrel and this Norinco.
Targets from this Norinco.
Feeler gauge? .005 from the end of the case to the breech face.
The High Road is not place for a man who knows a few things. I will leave you to your resident "Experts". I have spent most of my life with Heros and do not know how to behave with nameless cowards. Drive on!

 

[1911Tuner]

oh oh five

Feeler gauge? .005 from the end of the case to the breech face.


Now we're gettin' somewhere, Cap'n...One more little question.
Unless it's just the angle or the lighting, the pictures show that the case and the gauge are slightly below the barrel hood. Can't say exactly how much, but it appears to be more than .005 inch...which is just a tick more than
the thickness of a sheet of typing paper, and it appears to be at or near the bottom of the chamfer...the specs on which are 1/32nd inch at 45 degrees. Thatr would put the bottom of the chamfer at .0325 inch from the face of the hood. How did you determine the distance? If the case rim is below the hood by even .006 inch...and the rim is .005 inch from the breech face...that would make for a .001 inch interference fit between slide and barrel hood in battery.

If the pictures are showing the distance from the hood face to the rim...the case would be something close to .025 or .030 inch below that line,
and if the gauged distance between case rim and breech face is .005 inch...
the hood to breechface fit is...somewhat tight.


If you will...please gauge the distance from hood to breech face with the slide and barrel in battery.

Standin' by...

 

[One of Many]

Pictures do not tell complete story

I have been reading the thread for some time, and note that Mr. Sample likes to post photos as evidence of the correctness of his method. However, the photos do not show that the case length is correct (could be short) and they also do not show that the case has been inserted all of the way into the chamber.

These photos are useless for the purpose intended.

Headspace is not a function solely of the chamber depth and length of the hood. It can only be gauged when the frame, slide, and barrel are assembled and in the proper relationsip to each other (in battery).

I am not a gunsmith, but I did complete a multi-year course of training as a machinist, and worked in a machine shop until my heath required me to change professions. I returned to school and became an engineer. I have an analytical mind, and can spot a fallacious argument such as the one Mr. Sample has been professing.

I would not want to run the risk of firing one of Mr. Sample's products until it was checked out using the proper method and gauges. Some people are just lucky, and Mr. Sample seems to be lucky that none of his guns has (but how do we really know this) had a real problem with excessive headspace.

 

[1911Tuner]

Pictures are Worth...

Whoops! One of Many has just spotted the king's new clothes. Kudos, lad...and welcome to THR.

I had hoped to hold off for a while, but since we're into it this deep...I will make a standing offer.

If there is anyone who has plans to replace a barrel in the near future, and
is willing to sacrifice it for the sake of science...Send it to me, along with its parent slide. I'll set the chamber depth and barrel hood so that an .898
headspace gauge will sit dead flush...plus/minus .001 inch or less...and
still allow the gun to go to battery on a maximum .920 gauge with room to spare. No reamer will be used unless the chamber is below minimum length,
and only enough to bring it into spec. If the chamber is in-spec, neither the chamber shoulder nor the barrel hood will be touched except to bring it to within the tolerance that I specified.

The slide will not be touched by any cutting instrument, nor with any abrasive paper or compound.

With that done, I will create a condition of dangerously excessive headspace, that can be verified by any gunsmith who has the gauge set.
He will advise you not to fire the gun in this condition. If you elect to ignore that directive, I would advise mounting the gun in a vise and firing it with some sort of remote triggering device. I also advise that the magazine and the grip panels be removed. No sense in ruining a good magazine and grips.
the frame won't likely suffer serious damage.

Standin' by...

 

[OzarkExpedition]

Tuner - thanks for your response.

I guess that is just my take on how you write when dealing with Mr. Sample.

I dont want to get into a debate over what is right or wrong, not my place. I know that you have a responsibility here as a moderator but think there is another way to make your point. Not so much what you say but how you say it.

I know there is more history here than I want to deal with. I have read many, many posts by both of you. There always seems to be a right and wrong that follows.

Seems that I ruffled a few feathers by my post. It was never about how either of you do your gunsmithing.

I will rest here. At the very least I have upped my post count by 2, and that gets me closer to a WildAlaska group buy! Would prefer tp have changed the tone in the debate as that was my intention.

 

[1911Tuner]

Points

Howdy Ken,

No harm, no foul. I understand what you're sayin'...and you're right. There has been a runnin' love/hate thing with the Cap'n...and I get a little frustrated at times. Just for the record...I'm not a gunsmith either. I'm an armorer. The custom work, raceguns and comp guns aren't my area, and I don't even approach those technical questions other than for basic function
and troubleshooting suggestions. Those platforms are best left to the people who know the ropes.

Cheers! And Happy New Year...in 32 hours.

 

[1911Tuner]

Science

No takers.

Okay...I'll make it a little simpler. I still have Dominic's barrel. Open invitation to anyone within driving distance to come and see a loaded round and an .898
GO gauge sit flush with the barrel hood...and go to battery on a .920 NO GO
as slick as a button. Then, with the Colt barrel, the round and GO gauge will also sit flush with the hood, and not even come close to going into battery on the NO GO.

One of our moderators will be in the area soon, and we have a meet scheduled. I'll demonstrate it to him, have him report, and let everyone draw their own conclusions. Best I can do gang...

Sorry if I come across badly. I don't mean to. I'm just trying to provide correct information for those who want to know, and this tug of war is tiring me out.

Happy New Year to everybody in case I don't get back online before Saturday. Stay safe!

Tuner

 

[Jim K]

Headspace (long)

Being a "nameless coward", I don't know if I can put in $.02, but here goes anyway.

First, a lot of people prate about headspace in a rifle, but do not even think of the term in connection with a pistol or revolver. The principles are the same. Headspace is basically the space for the cartridge to fit between the breech face and the supporting area of the cartridge (rim, case mouth, shoulder, belt). That space could be set rigidly to an absolute figure, or to a very small tolerance.

The problem is that gun and cartridge manufacture, especially in wartime, is seldom that precise, primarily due to the need to use reamers as long as possible for economical production, both of guns and of cartridge making dies. So cartridge specifications are drawn on a plus/minus basis, with both a minimum and maximum for each dimension. Headspace specifications for guns are also plus/minus based on the cartridge specifications. The gun which will fire a given cartridge has to have its headspace adjusted so it will chamber the longest cartridge that is within specifications while still being safe with the shortest cartridge that is within specifications.

The GO gauge checks the first condition; the idea is easily understood - if the gauge won't fit, the longest cartridge will not fit. The second is less easily understood. The NO-GO gauge is longer than the GO gauge, made to incorporate the strength factor of the cartridge case, so that the shortest cartridge that is within spec will not stretch enough to break, or back out far enough for the case to fail. Because of the way pistols are used, and because of the stronger case relative to the pressures involved, this is less important in pistols than in rifles. (A rifle gauge set includes a Field Gauge, which is employed with used rifles to ensure that the headspace set at the factory or gun shop has not increased due to wear to the point of being dangerous.)

In any case, the critical measurement is between the cartridge support point (the case mouth in the .45 ACP) and the breech face at the point where it is solidly against its stop, whether the lug seats of a bolt action rifle or the slide lugs of a M1911 type pistol.

Why not use a cartridge as a gauge? True, most cartridges today are made very precisely, but it is just because they do vary that we really concern ourselves with headspace at all. So a cartridge case is not a very good indicator of headspace. And a cartridge may make a good GO gauge, but it cannot make a NO-GO gauge unless it is shimmed in some way.

Nor can we use the position of the cartridge in a barrel alone as an indicator of headspace. In the first place, the relationship between the barrel and the cartridge very rarely varies. But the relationship between the barrel and the locking areas of the breechblock may vary considerably due to wear, abuse, or mismatched parts.

Consider again a Mauser rifle. The cartridge may fit the barrel perfectly, but if the bolt lugs are battered at the rear, or the lug seats in the receiver are pounded down, or someone grinds a quarter inch off the rear of the lugs, the rifle will have excess headspace, no matter how good the relationship of cartridge and barrel may look.

My problem with this thread is that everyone seems to be using impromptu or home made gauges. I can see how someone trying to check out one rifle or pistol might resort to using shims or pieces of paper on a cartridge case, but I simply can't see how anyone who regularly works on a specific gun, like the Model 1911, would not have the appropriate headspace gauges. Come on guys; a set is $60 retail, a cheap price to pay to avoid guesswork.

Jim

 

[1911Tuner]

60 bucks

Jim...I think I gave 25 for mine way back when...and for certain applications
I made one each in .895 for a GO and .910 for a NO GO. Most people would be shocked to know how often some factory guns will chamber the NO GO...and how many will barely take the GO in recent times. Might partly explain the lack of feed and return to battery reliability that's been vexing so many new buyers. In the last three years, it's the rare barrel that I stick a finishing reamer in and not get chips.

The standard gauges are well worth the cost, even for non gunsmith folks. I've avoided buying an otherwise fine-lookin' pistol because it took the .920 gauge. That maximum gauge has paid for itself several times over because I've either backed away from a gun or had the price reduced enough to pay for a new barrel.

Have a good'un!

 

[Old Fuff]

On that "fine looking gun," did the go-gage indicate it might have too deep a chamber? I remembr one in particular where the owner found that the cartridge dropped in too far so he filed the end of the hood flush with the cartridge head. That he thought, solved the problem because "things looked like the should according to the picture in his book."

No, that didn't solve the problem, but it provided a graphic illustration of excessive headspace along with a loaded chamber indicator only the Brady Bunch could love ...

Concerning the cost of headspace gages. If someone is a "professional gunsmith" the cost of tools and equipment, including gages, is tax deductable. I can see no reason such individuals shouldn't have headspace gages for the cartridges/calibers they usually work on.

Concerning others: Perhaps a shooting club could purchase some sets using donated money given for that purpose, and then check competitors guns as a service. The same could be said about public shooting ranges and larger gun shops.

Last but not least, they don't cost so much that an interested individual couldn't purchase their own set(s). After all, they won't wear out.

What Jim Keenan said is absolutely correct, and military surplus rifles in particular should always be checked.

 

[mister2]

Headspace Precision

With all due respect, since this is about precision, is it possible to also be precise in communicating only the information necessary?

Sarcasm can be funny, sometimes.... but I come from a .308 community where losing part of my hand or face due to bad headspacing (or I used the wrong empty shell) is much ado about something, indeed.

I could assemble all day long using Federal Match (or an empty shell) and masking tape, but I wouldn't brag or even attempt to teach students (aren't we all?) other than Forster (or Clymer) Go, No-go AND Field.

And does it really matter if the truth is presented under a real name, or a pseudonym? Would the Forster specs change unless I signed my own name? As I respectfully requested, just the fax, M'am.

Thank you for your attention, back to your regular program.
MR2

 

[KMKeller]

Okay...I'll make it a little simpler. I still have Dominic's barrel. Open invitation to anyone within driving distance to come and see a loaded round and an .898
GO gauge sit flush with the barrel hood...and go to battery on a .920 NO GO
as slick as a button. Then, with the Colt barrel, the round and GO gauge will also sit flush with the hood, and not even come close to going into battery on the NO GO.

One of our moderators will be in the area soon, and we have a meet scheduled. I'll demonstrate it to him, have him report, and let everyone draw their own conclusions. Best I can do gang...

Sorry if I come across badly. I don't mean to. I'm just trying to provide correct information for those who want to know, and this tug of war is tiring me out.

Happy New Year to everybody in case I don't get back online before Saturday. Stay safe!

Tuner

'Tuner - You wanna do this on the 17th? I'd love to see it and I'll bring both of my 1911s for a checkout if'n you don't mind too much.

 

[jrhines]

In regard to the many ways to skin a cat... technical decisions should never be made by majority vote!

I said that.

 

[1911Tuner]

Many Questions

Fuff asked:
>On that "fine looking gun," did the go-gage indicate it might have too deep a chamber?<

Sometimes they did...sometimes they didn't. Most would accept a loaded round and sit nearly flush with the hood, or even dead flush...and STILL
close on a NO GO. Interesting how much difference a little mislocation on the lugs can make.
***************

Mister2 asked:

>>With all due respect, since this is about precision, is it possible to also be precise in communicating only the information necessary?<<

I'm tryin'...Lord knows I'm tryin.
***************

KMKeller asked:

>>>'Tuner - You wanna do this on the 17th? I'd love to see it and I'll bring both of my 1911s for a checkout if'n you don't mind too much<<<

Absolutely! Lookin' forward to another visit with you and Fed168...Wish
we could do another range trip this time. One warning though...You may have to fight me over that Rand.

jrhines said:

>>>>In regard to the many ways to skin a cat... technical decisions should never be made by majority vote!<<<<

Absolutely true...unless the majority votes to do it the right way.

Good chance that I'll hook up with one of the moderators...Steve Smith...when he's in the area. We had planned a face-to-face before he deployed to the Mid-East but it didn't pan out. If Dominic is okay with me hangin' onto that Norinco barrel for that long, Steve can be our non-biased
witness so we can settle this matter and move on.

To recap:

A GO gauge or a loaded round will sit flush with the barrel hood and go to battery easily on a .920 NO GO gauge in a Colt slide. The OEM Colt barrel will
show the same flush-fit, but won't come even close to chambering the NO GO. Additionally....the Norinco chamber is actually a bit short from hood face to shoulder at .893 inch. If it were even at the minimum of .898 inch, the headspace would be even more excessive. Dominic was extremely lucky in firing the gun in this condition.

Happy New Year to all!

 

[Dave Sample]