Headspace?

[Half Dog]

I recently meet 2 wonderful people who created a question in my mind.

I have a SA 1911 45 ACP and when a round loads into the chamber the extractor engages the brass. I have disassembled the pistol and have noticed that the extractor holds the case firmly against the face of the bolt (I'm guessing it is called a bolt). Because each piece of brass is not exactly the same length, I'm guessing that with every round, the mouth is not pressed against step inside of the chamber (please help with the correct terms) but is being held against the bolt face.

Questions:
1) Does the extractor engage as a round is being sheared from a magazine?
2) Does my extractor need to be adjusted?

Having asked all of this, I am wondering what will happen to the cycle operation if I put just a little too much taper crimp on a round. I am looking to get the proper tension but I need to understand the bigger picture.

Thanks in advance for your help.

[mozeppa]

all you need is enough taper that the round will pass the plunk test and you can't mash it in with your thumb.

and it's called a breech face, not bolt.

[OS OK]

I think the rim of the case slips between the breech face and the extractor as it is pushed into battery.

[Greg S]

You can do a plunk test to see how deep your chamber is. SAAMI is max of .920. You can use a cut off 308 case trimmed to .920 to check. Deep chambers will still function OK as you have observed the extractor will headspace the cartridge. Although functional, not ideal for match grade accurracy. Modern day 45 acp case come from the factory about .897-.899 oal.

The extractor adjustment is basically to hold the rim against the breech face. Two common adjustments are to tight causing a failure to return to battery from the cartridge not slipping under the extractor as it is stripped from the mag. This might be in part to tension but if the extractor has enough tension to hold a round on the breechface with the slide off the frame and the barrel removed the extractor might need alittle tuning and polishing.

The other common extractor problem is failure to extract which can be from a worn extractor, metal fatigue or clocking. Clocking or turning of the extractor is more associate with erratic ejection at different clock times as the firing pin stop to extractor fit is loose and allows the extractor to turn slightly in the tunnel. To check the extractor is running correctly, load a couple of mags with a single round, chamber the round, drop the mag and fire the round. If it ejects normally and to the side your ok. If it drops through the mag well or just drible out it either needs adjustment (tighter) or if it has some age on it 10 k plus you can adjust it but the metal is fatigued and will soon need adjustment again.

[Texas by God]

The case rim slides up into the extractor as the round is stripped from the magazine. A slight taper crimp is preferred. As previously stated remove your barrel and drop "plunk" a round in the chamber. The rim of the cartridge should be flush with the rear edge of the barrel. You didn't mention function- if your gun is working with your reloads you're probably doing it right.
Best, Thomas.

[Half Dog]

Thanks all for the information. I'm always looking to get better and wiser.

[wv109323]

If you are not experiencing problems then your extractor tension is OK. A test for extractor tension is take a loaded 230 grain loaded round. With the slide off the gun ,slide the round under the extractor. Hold the slide horizontal. If the round does not fall out you have enough extractor tension.

[35remington]

Despite what you may have heard or read, the 1911 headspaces on the case mouth much more often than on the extractor. The generous extractor/breechface gap sees that this is so.

[John 242]

Despite what you may have heard or read, the 1911 headspaces on the case mouth much more often than on the extractor. The generous extractor/breechface gap sees that this is so.

That's how I understand it too.
A long time ago there was a very informative post on 1911Forum.com in response to an article by a gun writer. http://forums.1911forum.com/showthread.php?t=442839

The post included pictures and measurements. In short, the gun would have to be ridiculously far out of headspace (or the case ridiculously short) before the extractor would play any part. To say that in a 1911 a cartridge headspaces on the extractor is incorrect.

From 1911 Forum-
192390

The 1911 uses an inertia firing pin. It has a lot of firing pin protrusion when pushed forward out of the breach face. Could a 1911 fire with a chamber so deep that the the case is held by the extractor? Probably. Is this normal? No.

Bob Dunlap did a video on headspace in which he and his protege Ken deepen a Mauser chamber to the point that they had to hit the firing pin with a hammer to get enough inertia for the gun to fire. In that case, the Mauser claw extractor was holding onto the cartridge, allowing the firing pin to hit it. Otherwise the cartridge would move so far forward, the gun wouldn't fire. Interesting stuff.

[John 242]

Because each piece of brass is not exactly the same length, I'm guessing that with every round, the mouth is not pressed against step inside of the chamber (please help with the correct terms) but is being held against the bolt face.

Not exactly. When the hammer hits the firing pin, it shoves the cartridge forward until the mouth hits the end of the chamber.



Questions:
1) Does the extractor engage as a round is being sheared from a magazine?
2) Does my extractor need to be adjusted?

1. Yes. The 1911 is a controlled round feed gun. As the cartridge is stripped from the magazine, it's nose moves up the feed ramp and and angles upwards towards the top (inside) of the chamber. As the slide continues forward, the rear of the cartridge clears the magazine feed lips, climbs up the breach face and slips in between the extractor and the slide. The rear end rises and the nose pivots downwards to align with the chamber.

2. a. If the extractor tension is too tight, the cartridge cannot climb up the breech face without binding or robbing energy from the slide. This can cause a complete failure to feed or a failure to fully return to battery.
b. If extractor tension is too loose, the gun will fail to extract and/or eject. Ejection is very dependent on extraction.

1911 extractors are not adjusted to hold the cartridge against the breach face. They are adjusted so that the cartridge rim is pinned against the left side of the breach (slide). The hook plays no part in this. The area before the hook is what controls extractor tension. The hook should not be digging into the extractor cut in the case. If it does, the extractor is improperly fit (Look at photo B in the above post).



Having asked all of this, I am wondering what will happen to the cycle operation if I put just a little too much taper crimp on a round. I am looking to get the proper tension but I need to understand the bigger picture.

Thanks in advance for your help.

I've never been able to put too much of a taper crimp on a .45 ACP but I suppose there's always a first time. You should have plenty of tension with a properly sized bullet and standard dies. If you don't, then something is not right.
If you load and unload a cartridge in a 1911 repeatedly, you will set the bullet back. This is true with factory self defense loads and reloads, regardless of taper crimp.

[David2011]

Other than correct extractor tuning the other key to headspacing for the 1911 is the crimp. There are roll and taper crimp dies so you have to be sure you're using a taper crimp die. The test can be visual; just make sure the crimp doesn't curve into the boolit. Adjust the crimp die down until the case diameter is .471-.469" just below the case mouth. There is probably a burr at the mouth so I measure a hundredth or two below the mouth. That's all there is to it. Since it's an O.D. measurement case thickness isn't a factor.