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Glocks I believe are as most centerfire delayed recoil operated guns in that the barrel moves a short distance with the slide in recoil, then the barrel stops while the slide continues rearward. The extractor hooks onto the rim of the case to pull the case from the barrel when the barrel stops in recoil and the slide continues reward. The ejector hits the opposite side of the case rim and kicks it off the extractor hook and the case flies out of the gun. Is the extractor what you are talking about?

Here is a schematic link and the extractor is #11.

http://www.brownells.com/schematics/Glock-/Models-17-39-sid858.aspx

When the slide closes on the loaded round, the extractor has snapped over the rim and protrudes from the slide which by chance indicates the chamber is loaded. Other guns use this way for loaded chamber detection. Some have a red dot painted on the top edge so the protrusion of the extractor is easily seen.

The headspace should be on the front of the case on the mouth of the case as in any other center fire gun of this type.

So…. The EXTRACTOR extracts the cartridge from the barrel and the EJECTOR ejects the case from the gun.

LDBennett
 

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I just read though this tread. I also already read the honady manual which I thought did a very good job of explaining it. I thought I understood it until I took a closer inspection of my new glock. I have never owned one before but I shot at least 20 of them and to my memory they all have the part I'm going to refer to. I pretty sure glock is going to call it there loaded chamber indicator. I was never sure why they but it on there because it is not very effective (not that I ever cared). After closer inspection it hooks into the rim of the case. Is these tiny part trying to control head space or is it spaced of the mouth like any other strait walled rimless case?
It headspaces on the mouth. I think you're seeing the extractor, which pulls the fired case back out of the chamber after you fire.
 

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You answered exactly a question I have long had: what keeps a straight-walled cartridge from sliding all the way into the barrel. Looking down the barrel of my Steyr S40, I can see the ridge you speak of where the cartridge seats against.
 

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Crimping = better accuracy and consistency. (tighter groups)
I get 3/4" groups without crimping in my bolt gun. My cases are neck turned though. Much easier to crimp I would think though. Only thing I crimp is for my semi-auto rifle and pistol. Whatever works for you.
 

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EXPLAINING HEADSPACE? THAT IS THE EMPTY SPACE IN OBAMA'S HEAD.
There is no empty space in his head.

He is doing exactly what he is told!! Many dont realize that anyone would do that be there you have a perfect example. There are many more exactly like him in different elected positions. I neednt name em.
 

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Alpo, great job explaining it and especially the descriptions for different types of cartridges. I knew the basics but not the information on some of those casings.

A question for you though. How can you adjust the headspace if it's off when you put together an AR from parts?
 

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Good question.

With a REAL gun :p a bolt or single shot, if you have inadequate headspace you have the chamber cut deeper. If you have excessive headspace you can have the barrel removed, the face machined down, then have it reinstalled one thread deeper, which gives you inadequate headspace, and you have the chamber recut.

If you are only going to shoot THAT gun in that cartridge, you can build a false shoulder on the case, fireform 'em to THAT gun and neck-size 'em.

But Mr. Stoner's Plastic Fantastic - I don't have a clue.

Sorry.
 

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With an AR with a headspace problem you have a couple of ways. First is to try a different bolt. The second would be to pull the barrel and then remove the barrel extension and mill the barrel and ream the chamber back to specs. You've got a new barrel and bolt so chances are slim that you'll have a headspace problem.
 

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Is the concept of MIL SPEC AR's to be able to randomly interchanging barrels (with barrel extensions installed) and bolts? Are the tolerances of manufacture and the specification of manufacture such that bolts can be interchanged as can be barrels and still maintain proper headspace tolerances?

Commercial rifles (bolt guns, semi-auto's, levers, pumps) appear to have to have hand fitting of the barrels for headspace. Is it possible that MIL SPEC AR's don't normally need headspace correction?

LDBennett
 

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That's the way I understand it LD. The Mil-spec barrels are head spaced during installation of the barrel extension with a mil-spec bolt. Theoretically, it doesn't matter what mil-spec bolt or barrel you use, head space will be correct.

All the stuff I keep seeing is "make sure you check the head space". The reality is though that if it's off a little, there's not really anything you can do about it because there isn't any reasonable way to adjust it anyway.
 

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like Tim I have read this in many places and as LD suggested this discussed to some degree in most reloading manuels..however...Alpo's explanation is so very concise that ther is almost no confusion inherent to it. i have always felt as if there was something i was missing in reading the reloading manuels..i now fell i really got the meaning!

THANKS ALPO!!!!
I have to say that I've read it before, have the hornady book, have a couple others, but his post was excellent and the point about which part of the case is the head was something that made the light go on for me.
 

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While it is true that the "step" in a pistol's chamber establishes the upper limit of case length, in reality the straight-walled rimless pistol cartridges only headspace on the case mouth in one special (and rare) circumstance: when the chamber is minimum length and the case is at maximum length. In most everyday instances, the headspace of these cartridges is established by the action of the extractor holding the case head snugly against the bolt face.

This is why it is so easy to fire a 9mm round in a .40S&W, or a .40S&W round in a .45ACP. If these cartridges were truly headspacing on the case mouth they would be rattling around loosely in those respective chambers and never allow the firing pin to make a firm hit.

This is also why it is so uncommon for reloaders to feel the need to trim straight-walled pistol brass. If these cartridges were truly headspacing on the case mouth, case length would be critical. In reality, they're not, and it isn't. Excessive case length only becomes an issue when the case grows so much that the case mouth is bumping up against that "step", in which case the weapon may not have enough headspace to go into battery. Pistol cases usually fail before they grow that much.
 

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Welcome to the forum, CaptainGyro. You've found a great place to be. There are probably centuries of experience and libraries of information in the combined membership here, and everyone is glad to help each other out. We're a friendly bunch and enjoy a good chat, a good laugh, and a good discussion. Pull up a keyboard and chair and enjoy!!

What do you shoot?

Be forwarned...this place can become addicting. :)
 

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Thank you very much for the welcome. I found the forum while looking for 76Highboy's LNL videos, and it struck me as an intelligent group of folks. I'll try not to drag down the average.

I like to shoot everything, but the hooligans I've fallen in with at the local club are all handgun enthusiasts, so that's where I've been spending most of my time lately. I really enjoy long-range precision rifle, but my local club is limited to 300 yards, so I haven't had the opportunity to really expand those horizons. I recently stumbled onto a Benelli M4 for a good price, so I've been dabbling in a little tactical shotgun too.

I do quite a bit of reloading, and am always anxious to learn something new or share what I've learned.

Again, thanks for the hospitality.
 
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I just found this picture, in Hatcher's Machine Guns.

Shows "Proper Headspace", and the result of "Excess Headspace". Notice the second drawing, the SLIGHT little bit of room between the cartridge head and the bolt face? That's all it takes.
Text Parallel Font Diagram Line art
 

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Thanks, Alpo;
That may help to solve a mystery. We were shooting black powder cartridge (Sharps 45-90), and for no apparent reason the cartridges started separating. One day it was shooting fine; the next it was broken cases. I'll pass this on.
 

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So Shoulder space or shoulder set back (adjustment) sets the head space on a bottle neck cartage, .002 on a bolt gun and .003 to .005 on semiautomatic?????
 

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There are NO STUPID questions but..... this is the reloading forum and it is assumed that people who come here care about reloading. Such people should read their reloading manuals. All the above info is in the reloading manuals introductory chapters. I urge all to read their manuals, and re-read them until they thoroughly understand at least the terms if not the process and the "why's" of those processes. The stickies above also are a good introduction if you at least understand some of the terms.

Those who come here to discuss commercial ammo (and that is just fine) might gain something by buying an reloading manual to get a better understanding of even commercially made ammo. I recommend the Hornady manual as it is very good at explaining the "how it works" of ammunition.

An informed reloader/shooter is at the first step of safety for reloading and shooting.

LDBennett
I know this is an old post, but this is some great advice. I do not reload. I buy commercial ammo. I love to read reloading manuals and all of you folk's posts on reloading. I've learned so much that I never would have.
Bravo LDBennet!
 
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