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Discussion Starter · #1 ·
While i understand heaspace such as in rifles im new to the 1911 and basically understand it but im confused about what the barrel hood and slide ledges were the barrel face rests have to do with headspace. I know if these barrel areas are to big the lugs in barrel and slide will not engage properly. This is what i found in a search on a gunsmithing site and and do not see it talked about much here , so here is the QUOTE i found:

"First , let me say that a small gap between the breech face and the end of the hood is desirable for reliable function. That this gap has anything to do with headspace is a common misconception. The headspace in a semi auto is the total room provided for the cartridge case,minus the length of the cartridge case."

"Now i will explain what i said. The headspace is fixed in any 1911 by the distance between the top lugs on the barrel and the breech in relation to the end of the chamber that stops the cartridge case. If this is confusing, think of it this way."

"The slide is machined with a fixed distance between the lug slots and the breech face. The barrel position is controlled by its lugs, and can only fit into this fixed space if the hood clears the breech face . The clearance should be enough to be sure of easy function even when severe fouling is present. "

"The depth of penetration of the cartridge into the barrel in relation to the lugs (chamber depth ) controls headspace because this is a fixed portion of the distance between the breech and the lugs. Headspace with any particular barrel/slide combination can be changed only by changing the chamber depth, or by replacing the barrel." end of quote.

I dont see this fixed distance in the slide talked about much when it comes to headspace but rather alot of talk about barrel hood fit . So i thought id pass this on to help others understand and to for discussion.
 

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Correct. There are some different views on hood clearance depending on purpose, but the headspace is solely determined by distance from chamber mouth to breechface.
Now the question-What is the ideal headspace? It is less than ordnance standard. What is the ideal hood clearance for reliability?
 

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Why do you think it's less than ordnance standard?

In my opinion, desirable specifications depend only on the intended purpose.

There is no one-size-fits-all set of specifications.

A weapon is a different thing than a game gun.

You don't drop a full race gun in the mud in the dark in a blind panic, root around, pick it up and empty it in desperation.

I'm not interested in finding out what a red dot sight does after it's been dropped when my life depends on it.

For a weapon, I want fixed sights that I can rack one-handed on my belt.

That's a different requirement than you would want for a bullseye competition, when the match will be cancelled if it rains, or if the sun isn't out.

The same is true (although to a lessor degree) for headspacing and hood clearance.

It's more important in a weapon that the weapon feed all the ammunition that would be used in it, every time, under all conditions, than it is to have a nice, tight fit with a particular, custom, hand loaded ammunition like you may want under other circumstances.

It depends on function. It depends on what you want to use the 1911 for.

The ordnance specifications are the gold standard for weapons.

So it depends on whether your 1911 is a weapon, or something else.
 

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Ordnance max spec is .022". At least twice what it needs to be even in your wildest combat fantasy.
Normal production standard is .01", I think .005 is more than adequate if the chamber is cut to normal max length. This would give you an easy .01" with most ammo.
Ordnance specs may be your gold standard, but many times they were an expedient to rapid manufacture and slap it together fitting. Pistols will work with excess headspace, but it really does not help function and hurts accuracy.
 

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Headspace

Jim Keenan said:
Headspace in a 1911 pistol is exactly the same as it is in any other gun. It is the distance between the support point for the cartridge and the breech face when the breech is closed.

Period.

Jim
Perfect answer Jim;

Clearance between the breechface and end of the barrel hood will result in linear movement of the barrel as the bullet moves down the bore. This may not be a problem with a short range combat gun, but it won't win many bullseye matches. Most gunsmiths set the headspace at .903 for accuracy guns, and as for reliability, most of these guns shoot many thousands of rounds per season and never miss a beat with chamber diameters set at minimum SAAMI spec. ...size(chamber) does matter....


Good luck

Jerry Keefer
 

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But for headspace purposes, the barrel hood is irrelevant. Many people believe that if the base of the cartridge is even with the back of the hood, headspace is OK and that the locking lugs and all that stuff doesn't really matter.

Jim
 

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Headspace

Jim Keenan said:
But for headspace purposes, the barrel hood is irrelevant. Many people believe that if the base of the cartridge is even with the back of the hood, headspace is OK and that the locking lugs and all that stuff doesn't really matter.

Jim
Jim;

When match barrels are fit to zero clearance between the breechface and upper locking lug, the short chamber is then reamed to a depth providing .005 headspace or .903 overall. Now, when the slide is in battery the cartridge case is seated in a space of .903 and can move only .005 within.
If clearance exists between the hood and breechface the barrel will move in a linear direction. Headspace and lock up is then no longer a constant. Great care is taken to get a "Jo-Block" fit between the hood / breech face and the upper lugs...
Take Care

Jerry
 

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headspace

Heres how my guru explained it to me word for word.

Distance from breechface to shoulder is static headspace.
Difference between case length and static headspace is working headspace.
Static headspace only changes when lugs deform with use.
Working headspace varies from shot to shot because case length varies.
Zero play between barrel hood and locking lugs doesnt mean anything except
that the slide and barrel lugs dont have any end play. You can still have too much headspace with zero play and you can still have good headspace with play. Case flush with barrel hood doesn't mean anything. You can have good or bad working headspace with or without a flush fit.

C-Buff
 

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Discussion Starter · #10 ·
Jim Keenan said:
But for headspace purposes, the barrel hood is irrelevant. Many people believe that if the base of the cartridge is even with the back of the hood, headspace is OK and that the locking lugs and all that stuff doesn't really matter.

Jim[/QUOTE


Guys thanks for the info its all making more sense. and Jim thanks for answering another question about the cartridge being level with the hood , ive read it before in several threads and didnt understand what the poster was getting at. More questions to come as i learn on my new Sistema .
 
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