You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an alternative browser.
You should upgrade or use an alternative browser.
Check headspace on a 45acp 1911
- Thread starter cw308
- Start date
Maximum chamber length is .920" for the 45 acp.
I'm curious where this number comes from. I've never heard anyone else mention it, so why do you think it's significant?
0.898" is the listed maximum case length. 1.275" is the maximum overall length with bullet.
It is rare to find a .45ACP case that exceeds .898". Unlike most other cases, .45ACP rarely stretches (grows) in length, and often cases get a bit shorter with firing.
Back to the 45, doesn't the headspace start at the end of the chamber off the case mount. Just trying to wrap my thinking around this.
NO, sorry, you are using the term incorrectly here.
Headspace is that distance from the surface of the barrel or chamber that prevents further forward movement of the cartridge, to the face of the bolt or breechlock when the action is fully closed.
The term comes from the earliest days of cartridge arms, and was, literally the space for the cartridge head (rim) to fit into.
The firing pin goes forward till it makes contact with the primer. There is no firing pin stop.
The 1911/A1 design has a firing pin stop. It's the plate at the rear of the slide that stops the firing pin from coming out of the back end of the slide.
A type of firing-pin in which the forward movement is restrained until it receives the energy from a hammer blow.
This type of system, where the firing pin is physically locked in place by another part(s) until the trigger is pulled, is genrally called a firing pin block.
The original 1911 design does not have this, the series 80 pistols (and up), do have this kind of system.
It is slightly recessed in the breech face before being struck by the hammer and is shorter in length than the housing in which it is contained. Upon hammer impact, it flies forward using only its own kinetic energy to fire the primer.
This is called an inertia firing pin, and is what the original 1911 used.
Your posted picture of the fireing pin. ..... Didn't think the pin came out that far.
The firing pin is tapered, and will stop when the fatter section wedges itself in the firing pin hole, but only if the firing pin spring is missing/broken. With the spring in place, functioning properly, it stops the firing pin's forward movement before then. However, this only applies when there is no round in the chamber. The firing pin in the picture is being pushed forward and held there so you can see it.
The maximum rim diameter is .480"
If larger, brass will not slide up my Gold Cups bolt face freely. Its to tight. Even with extractor removed.
If the case head is expanding (at all) your loads are TOO HOT.
And, remember that the Gold Cup is a match gun, deliberately made with tolerances on the tight end of the range. What chokes a Gold Cup may run flawlessly in a GI issue spec pistol.
Also I would point out that many of the tricks used loading bench rest rifle cases for best accuracy are usually ignored by the .45ACP and the semi auto pistols it is commonly shot from. The many factors present in the pistol cancel/override the accuracy improvement from specialized loading methods.
In other words, you won't get as much of a benefit, (if you get any noticeable benefit at all), which is why most of us don't bother. Things like seating the bullet just off the lands, neck sizing, etc., are accuracy advantages in a bolt action rifle and some other guns, but in a semi auto tilt barrel pistol, where the barrel moves in relation to the sights, not so much.
On firing of a 1911, just where is the extractor in relationship to the case rim?
Not sure just what you are asking here. The extractor hook will be in the case extractor groove. It may be in contact with the front of the case rim, or it may not be, there is some tolerance (slop) in the fit, there has to be some, but some guns have more than others.
When the primer is struck by the firing pin, the blow drives the case forward, until it is stopped, either by the ledge in the chamber, OR if not, by the extractor hook. When things are set up correctly, the extractor hook doesn't play that part, but things aren't always set up correctly. Generally, the case being held to the breechface by the extractor will allow grossly underlength cases to be fired, but its not a 100% given will always work kind of thing.
The usual way we test for correct case length (calling it headspace, incorrectly) is the "plunk test" Remove the barrel, hold it vertical, chamber up, and drop a loaded round (or sized case -not flared) into the chamber. "plunk".
The base of the case should be flush with the barrel hood (that part of the barrel that is uppermost as you hold it). Cases below flush are short (though they may fire ok) cases that stick up above the barrel hold are too long, and may interfere with proper lock up of the gun.
Generally speaking, most semi autos function (feed) better with rounds slightly shorter than listed max COAL (loaded length with bullet).
For your reading pleasure. http://www.saami.org/specifications_and_information/index.cfm?page=CC
James K
You sound like a rifle shooter like myself. All my cases lengthened, trimmed with every firing to the same length. With 45acp it seems like its a different animal. Its only my second time on resizing. As odd as it seems, it looks that way so far. Learn something new every day. Be Well
Chris
You sound like a rifle shooter like myself. All my cases lengthened, trimmed with every firing to the same length. With 45acp it seems like its a different animal. Its only my second time on resizing. As odd as it seems, it looks that way so far. Learn something new every day. Be Well
Chris