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Here I thought I knew a few items about the 45 ACP cartridge.
I was under the impression that this case in the Colt 1911 style pistol's headspaced off the case mouth. I had an individual who I respect on information about guns tell me that the bolt face and extractor determind the headspace for a 45 ACP colt.
I started to disagree than thought I would tone down listen and than come on line and ask.
Anybody have .02 worth on this?
 

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Proper headspace on the 1911 pistols with straight cases is set by the case mouth. Some degree of control CAN be determined by the extractor hook, but it is variable. Easy to see in practice...the .38 Super 1911s originally headspaced on the semi-rim and, to a degree, extractor. At that time, .38 Super 1911 had a well deserved reputation as being inaccurate. When headspace control was switched to the case mouth, like on the .45 ACP, those "inaccurate" stories vanished
 

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I agree with Charley, the .45 ACP round is designed to headspace on the casemouth. The barrel's chamber is machined with a shoulder to stop the forward movement of the round. All factory ammo, as well as GI ball ammo, is straight right up to the casemouth. While the extractor may influence headspace, it is not the standard from which headspace is established.
 

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Discussion Starter #4
I certainly will not be shooting any reloads from this guy.
I always worry about the crimp on this type of case so I dont reload them or shoot other folks reloads for that reason.
I understand what is needed but there is no standard to compare to like a measurment. I thought that maybe a crimping only die would help but you probably have to adjust by trial and error also. I know that I lack confidance on this because so many reload this round any way.
 

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Measurement is .898 inches, if I remember correctly. As far as crimp is concerned, just use a die that taper crimps, and cartridge OAL is not a problem.
 

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The .45 ACP cartridge case is very stout and loaded within reason, not prone to stretching so once checked for OAL, they will last a long time without trimming. A good taper crimp is sufficent enough to keep a cast bullet from shifting under recoil. I have reloaded thousands of rounds this way and shot them in bullseye competition without a hitch.
 

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Get a mic. and measure a fist full of fired .45acp cases....then measure the ACUTUAL lenght of the chamber in your pistol's barrel. IF it's a box-stock pistol, may woinder how the minimum case lenght ever ignites in that barrel.

Most bullseye/ target shooters will seat their SWC's so that the leading edge of the SWC is just about touching the riling...not just for bullet "jump", it also helps to control headspace.
 

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The older 45acp had longer and wider chambers. The original intent of the 45 was reliability in wartime conditions meaning dirty and fouled. If you took the barrel out of a standard 45 and one from a national match you could easily see the difference in chamber looseness and length by dropping a round in the chamber. The newer model 45 have a lot tighter dimemtions for better acuracy. Even if the chamber were way too long I believe the 45s design would allow it to fire. The extractor would hold the round in place.
 

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take a factory round and drop it into a 1911 barrel that has been removed from the gun. it will put the base of the cartridge about even with the barrel hood. now take a cartridge and stick it under the extractor in the slide (also removed from the frame) and see how much slop you can get between the breech face and the brass. even the sloppy wartime barrels will probably headspace better than any match extractor.
the extractor is commonly tuned and a big part of this tuning is shaping the hook on the business end. this is done for feeding reliability only, and headspace does not enter the equation. (at least not in anything i've read)

monty
 

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ironhead7544 said:
One other thing: the 45 acp case is slightly tapered.
You're absolutely RIGHT about this but I might add it becomes a straight walled case with a "hump" near the rim after going through my carbide die. :D
 

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monty said:
take a cartridge and stick it under the extractor in the slide (also removed from the frame) and see how much slop you can get between the breech face and the brass. even the sloppy wartime barrels will probably headspace better than any match extractor.
the extractor is commonly tuned and a big part of this tuning is shaping the hook on the business end. this is done for feeding reliability only, and headspace does not enter the equation. monty
Totally agree. The extractor needs all that clearance in the hook to function properly given that there are dimensional differences in the cartridge rim due to manufacturing and extended use. I had some GI WCC brass that I shot so much that the rims would no longer enter my case gauge yet the extractor just kept functioning. When things got to that point, the fired brass was left on the range floor.
 

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Tolerances were more generous druing WWII...and a lot of the "goose-loose" reputaion of the 1911 comes from this past...deosn't have a lot to do with today's production guns.

Pulled out two WWII barrels. Measured, the chamber depth is running .900" on one and .902" on the other ...not too bad for MAX. length (lyman's figures) .898" cases.

Picked some cases from their lots, everything from RA 1960 Match to Federals...the longest once fired case reads .892", the average is .889".

Never had to trim a .45acp case for being over max. in my life.

Full length resized, they "grew" .003" in the dies at hand (RCBS)....neck sized (in a 310 tool) they don't grow enough to measure. Ironing out that case full length does force the brass to lengthen.

So we have resized cases running .892" on the average...and chambers on these 60year old barrels at .901"...for .009" of "slack". If you were to trim them to the recommended .888" minimum (Lyman's figures) then you'd have .013" of slack in these old barrels.
 

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Headspace on the extractor?

44SandW said:
Is anyone stupid enough to?
44SandW:
The question of firing the .45 GAP in a .45 ACP chamber is relevant to the question at hand: Does the 1911 pistol design headspace off the case length or the extractor. Given the controlled feed action of a properly sprung 1911 the shorter cartridge would be held closely to the breech face and fire normally. In addition the GAP and the +P ACP work at the same pressure.

Note: I am not recommending the practice. However, this will happen at some point, ("I need a box of .45s for my Glock"). I also suspect this combination has been tried by both ammo and gun manufacturers.

Finally: Injecting the word "Stupid" into this type of forum stifles intelligent discussion and should be avoided.

Ralph
 

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Well please dont preach to me.

In all honesty is it a smart practice? They are two differnt designed to go into two differnt chambers would you fire a .44 mag in a .45 Colt chamber? Just because it CAN be done doesn't mean its smart.

The word stupid is just fine its not like my sentences are as follows:

"Well anyone that does that is %@##%^@#@#^@# and !^#@^@$#&"

They are free of vulgar and not aimed at anyone. it does not "stifle" intellectual conversation nor did it stop you from an intellegent responce.
 

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ribbonstone said:
If you were to trim them to the recommended .888" minimum (Lyman's figures) then you'd have .013" of slack in these old barrels.
i think that firing pin protrusion is supposed to be .055"-.065" so with minimum firing pin protrusion and minimum case length, you will still have a .042" dent in the primer.

the only holes in my story here is the .055"-.065" dimension came from directions for installing a Gentry safety on a Remington rifle, and i'm assuming the same for the 1911 for the purpose of this conversation. :D

(i don't have my .45 handy to measure right now)

i'm gonna move on before this one gets locked.

monty
 

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Ok, gents, calm down. There's a few reports of .45 GAP being fired in .45 ACPs floating around on the web already. It's happened with guns of other calibre before and it will happen again. And yes, there are people who shouldn't play with guns.

Here's an interesting tidbit that turns headspacing on the extractor from a possibility to a probability. Minimum headspace is .898", as mentioned earlier. Maximum headspace is .920", .022" greater. That's almost 4X the usual .006" tolerance we see in a .30-06 or a S&W revolver. Just adding all the tolerances puts the rim on the hook if everything is loosey-goosey.

Firing pin protrusion looks like a 1/4" on mine. It depends on the return spring, but it's lots enough to reach anything anyone's likely to try chambering.

Bye
Jack
 

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That pin has more than enough reach (at least the Colt type inertia pins) to fire anything likely or UNLIKELY to be fit into the chamber.

The excess headspace may have an accuracy effect, but at the pressure the .45acp runs at, it's more likely to beat the case heads up than to cause any real gun damage. IF after five or six loadings, you find the cases reluctant to enter the shell holder or giving some feeding problems...carefull measure might find that they are no longer "rimless"..the rims are now larger (and thinner) from the peening.


Disclaimer: this is what WAS done back in the day...not what should be done now that we know more about what makes gun's tick...so keep it in context of the time frame.

What old guys did, back in the day that loading dies were steel and not carbide, was to push the WHOLE CASE theough the steel die stripped of it's decapping rod. The alternative is to push the case in a bit past the rim...allwoing the die to swage the rim back to rimless...and driving it out. OF the two, pushing the case all the way through is a LOT faster, but it does over size the case. Don't try that with a carbide die or you may ruin it once the solid part of the case enters the die.
 
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