Headspace Defined !

[Timothy]

I've loaded probably 3000 rounds between my 22-250, 7-30 Waters, 38 Special and 44 Mag. Not alot compared to most of you guys, I'm sure, so that is why I am asking the following:

Headspace, as I understand it, is the amount of space between a case head and the breech face in a fully closed action.

What my thick Irish head has a problem with is completely understanding what exactly "headspaces off of" means.

i.e. "It headspaces of the shoulder" ......or "It headspaces of the case mouth"

Am I on the right track by figuring that all chambers have a given amount of front to rear space in which a loaded round can move and in some chambers that "room to play" starts at the case mouth and in others it starts at the shoulder?

[WESHOOT2]

"Headspace" is at the case mouth.

Remember that in your auto-pistol the extractor will hold the cartridge against the breechface.

[B9mmHP]

Timothy, as said by Weshoots2. Simi-auto pistols, headspace on the mouth of the case,rimless and rebated rifle cartrages headspace off the shoulder,belted off the forward edge of the belt,rimmed and simi-rimed off the forward edge of the recess provided for the rim. All are measured from the boltface.
A slight gap is ok .005" to.006" it depends on what is allowed for any perticular gun.
You should be able to find this info in any good reloading manual. It is important that you do not have excessive headspace.

[Timothy]

Thank you guys for your replies:
After looking at my post, I realized some spelling errors ( not unlike me)

I guess what I'm asking is this: When you say " it headspaces on the mouth" exactly what does that statement mean. Could you tell me that statement in other words?

[Keith J]

A semi-auto straight walled case like a .45 ACP, dropped into the chamber of the pistol will stop when the mouth hits a small shoulder in the chamber. The distance from this shoulder to the rear most part of the chamber is the headspace.

On a rimmed case, like the 30-30, .38 Special etc is headspaced off the thickness of the rim.

Rimless cases like .22-250 are headspaced off the shoulder. In reloading, one can push this shoulder back, making a case that is shorter than the chamber. This is not a good thing as the brass will fail with repeated loadings.

[Art Eatman]

If a rimless rifle cartridge is either shortened in reloading, or is fired in a rifle which has a chamber which is too large, the rear of the case--the case head--may not be firm against the bolt-face. However, the firing pin may still be able to hit the primer.

It is possible, then, for the primer to be blown out, letting the shooter discover the result of very high pressure gases venting through the action of the rifle. In some older bolt designs, the firing pin can be blown out into the shooter's face. Not good.

Regards, Art

[Bud Helms]

WESHOOT2, B9mmHP,

I'm interested in your take on this article:

The dangers of shooting the .40 S&W in a pistol chambered for 10mm

[WESHOOT2]

Sensop,


Makes complete sense to me.

Firing cartridges in chambers of another caliber is a dangerous stunt. Possible, but poorly considered.

[Bud Helms]

Yeah, great title. But, I was wondering what you thought of the discussion of headspace and use of the term "standoff"?

[B9mmHP]

sensop
I am not sure about the term "standoff".
The point the artical was making is the two 10mm & 40S$W do not have the same headspace and should not be used in differant cal. guns. The reffrence he made to the 38 and 357 are cartridges used in a revolver that headspacess on the rim and not on the mouth of the case. Case length is not that important in a revolver, but very important is a simi-auto.
It would be kinda like droping a 308 rifle cartridge in a 30-06 a no no, the two are so close "not in headspace' that you can buy inserts to install in the 30-06 so you can shoot 308s. Hope that helps.

[MLP]

sensop,

What is meant by "Stand-Off" is the fact that the round is fired when the case head is not in contact (or very very close proximity) with the breechface. ie: it stands off the breechface. It is only possible for a round to be fired in this instance if the firing pin is long enough to reach the primer with the cartridge sitting this far forward.

Now I in now way endorse firing the 40S&W in a 10mm, though I have done it. In this article they have sighted differing case diameters as the cause of this happening. They said that the .03mm or as in my books .001" difference in case size at the base (.425" for the 10mm and .424" for the 40S&W) is what caused the case to slip out from under the extractor. Well I say this is nonsense!! Reason is the my bran new 10mm cases from Winchester measure .418" at the base. if this were a problem I am sure we would see many failures to extract. My reasoning for the problem they experienced is that there was either a weak spring on the extractor or the extractor hook was worn or not in spec.

I know, that is really kind of irrelevant, but it is my take on that part of the article.

While in a perfect world, we understand that a case is suppose to headspace off the case mouth, case shoulder, case belt or case rim, depending on the specific cartridge. However, I am sure most of us would agree that in real life the case is held in place by the extractor and in essence headspaces off the extractor. And yes this would only apply for the first time fired with a shouldered case, unless full length sized every time.

__________________
Keep It In The 10 Ring,
Michael


[I]"We find comfort among those who agree with us - growth among those who don't."[I]

[Bud Helms]

Let me start this post off by saying I am not trying to start a "Definition of Headspace" flame war/argument. In fact, I think there's more agreement here than not.

My whole point concerns the use of the term headspace ... anal retentive, I know. I use headspace as a verb as much as anyone. But it came to mind a few months back in a thread discussing headspace for rimless, straight-walled, auto pistol cartridges, that everyone agrees that they headspace on the case mouth, by definition. Then we proceed to talk about the extractor as where the cartridge headspaces. Yes, it is the head of the case and, yes, the extractor minimizes the space off the head. But here's an epiphany for you ... that's not headspace!

It's very confusing for someone trying to understand the term. I say we misuse it. When I read Dean Speir's article, the light came on. It seems perfectly natural to me to think of headspace as the distance from the breech face to the case mouth "step" in the chamber, since that's the first "definition" I ever learned, and the only definition, per se, you will find. But I wonder if you can see the problem when in the very next sentence, we say the cartridge "headspaces off the extractor"? Which is it? For someone just getting into reloading, it's a muddle.

In that previous thread to which I referred, there was an abundance of quotes and references to experts' opinions on the subject. It didn't help explain the problem. It just firmed up what I think is a misuse, through practice, of the term headspace, in this particular case, if not others.

I say, if we leave the definition of the term headspace alone and refer to the intimate relationship between the case head and the breech face as "standoff", then the problem is solved. It is after all, just terminology. And the cartridge really doesn't "headspace" off the extractor, the extractor prevents excessive "standoff" ... don't you agree? Or are you convinced, by repeated usage, that these cartridges "headspace" off the extractor?

What say you? If we don't agree on this, I think we'll all live. It's not the end of the world, just an opinion.

[MLP]

sensop,

I think that we, for the most part, are in agreement here.

Headspace, by definition is; the linear measurement from the breechface to what ever retaining surface stops forward travel of the cartridge.

Stand-Off, by definition is; the distance between the breechface and the case head as controlled by the extractor. (And yes, I agree, this is Not headspace! Though many (myself included) have, on more than one occasion, referred to it as such).

Yes it can get real muddy trying to explain this to someone new to reloading and trying to digest all the necessary information, to safely start reloading, in a way that makes sense to them.

I would have liked to been here for that other discussion. As when it comes down to defining headspace, one needs to look at the spirit of the definition not the letter of the definition.

Stand-Off, on the other hand is a very good way to describe what the extractor controls. Especially when in reference to strait-walled rimless cases. And even on shouldered cases that have never been fired or have been full length resized, as these do not actually reach the headspacing shoulder in the chamber. Just as the rimless pistol brass does not reach the headspacing step in the chamber.

While headspace describes the max length possible for a case dimension that still allows closing "into battery" of the action.

So ya, I think we are in agreement on this.

__________________
Keep It In The 10 Ring,
Michael


[I]"We find comfort among those who agree with us - growth among those who don't."[I]

[WESHOOT2]

English is easy to mangle, eh?

[B9mmHP]

sensop. I don`t want to beat this horse to death, but.

Yes. The cartridge really Dose Not "headspace" off the extractor. The purpose of an extractor is to remove a fired or unfired cartridge from the bore.
No. The extractor Does Not prevent excesive "standoff". It may hold the cartridge tight to the boltface, but it just pulls the cartridge away from where it should have contact in or at the bore,so you still have a dangerous situation.

[MLP]

B9mmHP,

What sensop and myself were discussion the improper use of terms, especially when explaining headspace to a newcomer to reloading.

For instance here is a quote of someone else's reply to a newcomer just this morning:

Many 1911 pattern guns will in fact headspace off the extractor rather than the case mouth.

Yes, in essence this is exactly what is happening, but in definition of the term "Headspace" this is a totally false statement.

You said:

It may hold the cartridge tight to the boltface, but it just pulls the cartridge away from where it should have contact in or at the bore,so you still have a dangerous situation.

How do you figure?? Now I am asking that Q in reference to proper matching of a cartridge to a chamber, say a .45ACP cartridge in a .45ACP chamber or a 30-06 cartridge in a 30-06 chamber, not putting a .308 cartridge in a 30-06, as that is a no brainer!! Not to mention irrelevant to the discussion at hand.

Nothing is exact, there are ± tolerances to every dimension on anything we deal with. So a cartridge at the - tolerance and a chamber at the + tolerance will leave excessive space, but has been deemed safe by the SAAMI.

Actually what IMHO gets a little unsafe is when the extractor fails to hold the case head in contact with the breechface. In this case when the round is fired when not in contact with the breechface, pressure can push the primer out of its pocket, usually the primer gets pierced, the recoiling case hammers the breechface and makes it impossible to read pressure indications on the case.

With a shouldered case, such as a 30-06, a bran new case will usually Not reach the headspacing shoulder in the chamber, this in fact is the norm. Now firing this cartridge, when held tightly against the breechface, allow the case to expand laterally out to fill the chamber. This is much less abusive to the weapon and brass both, than for it to hammer back into the breechface. Now after this case has been fired in a particular weapon, it fits that weapons chamber exactly. Now neck sizing is the way to go if the case is to be fired in that weapon again, as it is matched to that weapons chamber. If you full length size the case it has to swell all over again, so now you do not have a matched case and it shortens the life of the case. Now if that case is to be fired in another weapon, it definitely should be full length resized. Reason for this is that if the last chamber it was fired in was on the + side of tolerances and the next weapons chamber is on the - side of the tolerance, then you will actually have to crush the case a bit to close the action into battery!

On a strait walled auto pistol cartridge like the .45ACP this is kind of irrelevant as long as the case does not exceed maximum case length since it is full length resized every time and the case (99.9% of the time) is too short to reach the headspacing step in the chamber. And, IMHO, all the headspacing step in the chamber does is keep the round from falling too deep into the chamber, allowing the extractor to keep a good grip on the rim and hold it tightly against the breechface. If this is failing to happen, then either the case is too short and/or there is a problem with the extractor or extractor spring.

So, B9mmHP, I ask again: How do you figure in your quote above that it is a dangerous situation??

__________________
Keep It In The 10 Ring,
Michael

[I]"We find comfort among those who agree with us - growth among those who don't."[I]

[Dean Speir]

They said that the .03mm or as in my books .001" difference in case size at the base (.425" for the 10mm and .424" for the 40S&W) is what caused the case to slip out from under the extractor. Well I say this is nonsense!!

Well, I is "they," and I say that someone didn't read very carefully. The passage referenced actually reads:

The operative term here is "Stand-Off," where the .40 S&W (actually 0.03mm narrower than the 10mm) is somehow slipping past the extractor and head-spacing on the case mouth deep in the 10mm chamber, leaving 1/8" of "stand-off" between the case head and the breechface.

Now I wasn't invited over here to get into a peeing match over nomenclature or to make invidious commentary about other people's reading skills, so I'll simply say that I performed the range tests, discovered the anomaly, learned the term "stand-off" from my friend and colleage Farmer Frank James (who probably himself learned it at the knee of Elmer Keith), and reported on it, first in a Petersen's piece some years ago, and then when I launched The Gun Zone.

The message is simple: wanna shoot .40 S&W in a 10mm autopistol, make sure it's one of those utilizing the Peters-Stahl slide with the dual extractors. Otherwise ya makes your choices and ya takes your chances… as it is with real life.

Good discussion going, though.

Happy New Year! Stay Safe…

[MLP]

Hi Dean,

My Bad! My intent with that statement was not to offend. So if I did, accept my apology. When I reference to an article like that in a discussion it is basically a third person type of response as opposed to when I am actually addressing the person that has made the statements. At which time the statement would be posed more in the way of a question to clear up any misunderstanding of how it was written, before disagreeing with it.

I would have dropped you an e-mail about it, however, your name at the bottom of the article did not have an e-mail addy associated with it. I admit I was a bit lazy and did not search the site to see if I could find your e-mail addy. I have since corrected that.

I am all for discussing things, as this is IMHO one of the best ways we have of learning and expanding our knowledge and understanding of things. It is great when we all agree, however, when we disagree on something, then one or all of us stand to learn something new.

Yes, maybe I did read something into your statement:

The operative term here is "Stand-Off," where the .40 S&W (actually 0.03mm narrower than the 10mm) is somehow slipping past the extractor and head-spacing on the case mouth deep in the 10mm chamber, leaving 1/8" of "stand-off" between the case head and the breechface.

as I took it you meant that this 0.03mm (0.001") diameter difference was the cause of the .40S&W case slipping past the extractor. In re-reading it and reading the parenthesis area as a side note, which I now believe that is the way it was originally intended, you are simply saying that "somehow" the case is slipping past the extractor. I also understand that the 40S&W case, being 0.142" (or just over 1/8") shorter than the 10mm case, it is not being pushed back up under the extractor by the headspacing step, as it would be with the proper length 10mm case. This is causing the 1/8" of "Stand-Off" between the breechface and the case head.

So that would clear up my misunderstanding of what you originally said.
Then I would pose my question to you:
Do you think (through observation of the firearm used in this test) that it was possibly a weak extractor spring or a worn tip on the extractor that was allowing the 40S&W case to come out from under the extractor when the slide slams forward into battery??

The reason I ask this is just for simple expansion of knowledge. Like I mentioned I have fired 40S&W out of a 10mm gun. This was back in the early mid 90's and out of a Glock G20. I personally have no real use for doing such, and only did back then at the request / inquire of some people wanting to know if it would work and what problems could arise from it. I never experienced the problem you described. So it makes me wonder about the extractor or its spring. However, I did find that feeding was not 100% reliable with the shorter COL of the 40S&W in the 10mm action.

I do agree if one wanted to do this, (and I can really see no reason why a person with a 10mm would want to fire 40S&W out of it, short of the cost difference in ammo, however, that person should be looking to buy a 40S&W, IMHO), it would be best done in a gun utilizing a Peters-Stahl slide. Like an Omega for instance. Still, I recommend against it, unless it be an emergency. However, others choose as they choose to do, no matter the advice they are given.


Back to the actual topic of this thread. Dean, your article got brought into this thread to introduce the term "Stand-Off". (Not to dispute your article. Again I apologize for that). This is a new word for me! However, I think it has its place in the glossary of reloading manuals.

So I am curious, Do I and sensop have a fairly good understanding, IYO (in your opinion) of the meaning of the term, Stand-Off?

Thanks for your time, and please, don't be a stranger to this site.

Enjoy and Happy New Year!

__________________
Keep It In The 10 Ring,
Michael

"Men occasionally stumble over the truth, but most of them pick themselves up and hurry off as if nothing had happened." - Sir Winston Churchill

[Bud Helms]

Thanks for stopping by, Dean. As MLP said, don't be a stranger. I see you have posted before.

For those of you who don't know Dean (I have no special permission to introduce him, nor are we lifelong buddies), he is the Sports.Rec Community Leader on Prodigy.net. He has some great info and a collection of interesting articles there.

Here is an excerpt from Dean's Gun Zone Front Page

From an Iver Johnson advertisement, circa 1904:
If householders were required by law to own and know how to use revolvers, burglary would cease. It is an act of good citizenship
to make crime dangerous -- an encouragement of crime to remain defenseless.

Also, go to the GunZone and read the Maintainer's Credo.

[Dean Speir]

I would have dropped you an e-mail about it, however, your name at the bottom of the article did not have an e-mail addy associated with it. I admit I was a bit lazy and did not search the site to see if I could find your e-mail addy. I have since corrected that.

Hey!, thanks for the idea… the reason I was delayed in responding to this was that I was running all over TGZ addressing that issue! I appreciate the input, and have acted on it.

Yes, maybe I did read something into your statement: "The operative term here is 'Stand-Off,' where the .40 S&W (actually 0.03mm narrower than the 10mm) is somehow slipping past the extractor and head-spacing on the case mouth deep in the 10mm chamber, leaving 1/8" of 'stand-off' between the case head and the breechface." as I took it you meant that this 0.03mm (0.001") diameter difference was the cause of the .40S&W case slipping past the extractor. In re-reading it and reading the parenthesis area as a side note, which I now believe that is the way it was originally intended, you are simply saying that "somehow" the case is slipping past the extractor.

There are a number of possible reasons for that, and that rim datum may have been contributory. Or it may be that the extractor is being asked to perform a task for which it was not designed. Or… or… or…. Doesn't matter, really, as it was a parenthetical remark… and those have gotten me into trouble before.

Do you think (through observation of the firearm used in this test) that it was possibly a weak extractor spring or a worn tip on the extractor that was allowing the 40S&W case to come out from under the extractor when the slide slams back into battery??

The pistol, a Model 1076 S&W of the type issued to the FBI, was a T&E gun on loan from Smith & Wesson (I can still say that name here, can't I?). It was a low round count model at the time I performed the initial test which led me to correlate the ironed caseheads and pierced and/or flowing primers with the anomalous chronograph figures. I did inspect the pistol more closely before continuing the expanded mission-specific range session, and the extractor was, by all appearances, completely intact, and was after the test as well. The pistol worked flawlessly with both full and demi-powered (thank you, Uncle Jeff!) 10mm rounds the entire time I had it, so I have no reason to think that any component was other than in AA+ shape. (One thing I do in hindsight regret is that I never quantitatively measured the extractor tension at three different stages of the process, but quite frankly, I didn't know how!)

I never experienced the problem you described. So it makes me wonder about the extractor or its spring.

BTW, upon information and belief, the extractor is the spring.

And to touch on this component one last time, I have seen extractors (primarily in Colt's/Browning pattern guns) go tango uniform in all sorts of situations, and when it does, you're SOL. On more than one occassion, shooters have offered me their first born or their girlfriend in exchange for the spare 1911-type extractor I keep in they ditty bag inside my range bag. But the only time it happened to me, was in my basement at the bench. I had a miscellaneous piece of .45 ACP primed brass that for reasons which now elude me, I determined should be touched off in my working gun (PDW). I did it, and heard something hit the concrete when I removed the magazine. A cursory look revealed nothing, but when I racked the slide to eject the fire case… and it didn't pop out… I knew precisely what I had heard: the broken extractor hook. More physics were learned that day, I can assure you!

I have fired 40S&W out of a 10mm gun. This was back in the early mid 90's and out of a Glock G20. I personally have no real use for doing such, and only did back then at the request / inquire of some people wanting to know if it would work and what problems could arise from it.

One of the savviest guys I ever met, the late Roger Tucker (one of Walt Rauch's crew), carried a Delta Elite charged with .40 S&W rounds! I remember when I learned this, when we were all out at Gunsite for NTI IV back in '94, and Frank James and I looked at him like, [color=#FF0000]█[/color][color=#FF0000]█[/color][color=#FF0000]█[/color]?!?, and Roger said in that quiet, level way of his, "I'm not supposed to be doing that, I guess… is that it?" And he was serious. Farmer Frank and I stopped what we were doing, and gave him a quick run-down on the risks involved. Roger thanked us… and kept right on shooting those .40 S&Ws in his 10mm pistol. According to Walt, he never had an untoward event related to that. (Apparently though a job, Roger had access to lots of .40 S&W ammunition, whereas he would have had to purchase any 10mm out of pocket… what Ken Hackathorn refers to as habius grabus prevailed. Us gunzine byliners always have the time-honored traditions of "gunwriter graft" as a fall-back, of course.)

O, well…

Do I and sensop have a fairly good understanding, (in your opinion) of the meaning of the term, Stand-Off?

Seems so… though Sensop sure has worried it to death, I think.

Thanks for the invite… I administer four BBs elsewhere so I don't get over here too often. Usually it's because someone tips me to a particular thread and asks for some specific input.

Have a safe New Year's weekend.

[B9mmHP]

MLP.

My statement on the extractor holding the cartridge to the bolt face Does Not prevent excessive headspace. I still say that.
This Topic started out "Headspace Defined" and we covered that topic a lot, so I will try to answer your Q on my statement without getting to involved, because I have to hunt and peck on this computer.

If the cartridge "case" is to short "excessive headspace". 45ACP, 30-06 and others. ( Short meaning not long enough to properly headspace, or come close +- to the bolt face and in the chamber where the other point of the headspacing happens.)

When the firing pin strickes the cartridge " primer" it moves forward to meet the chamber where it headspaces from, the powder ignites, since the cartridge is no longer in contact with the bolt face the primer backs out, the case expands to meet the chamber walls, just like it was meant to do. But the rear section of the case is no longer supported by the bolt face and the pressure in the chamber pushes the head of the case back to the bolt face, which can cause case head seperation.

Now for those that don`t trim your cases.
If the cartridge case is to long "overlength" the case mouth can be pushed into the throat of the barrel "where the bullet lives" and crimp the case mouth further. And in the throut thier is no room for the case to expand to release the bullet, so you end up with excessive chamber pressure.

As for the 308/30-06 maybe that wasn`t a good thought, but since it was brought up. You don`t want to fire a 270 cartridge in a 7mm eather, like not shooting a 10mm cartridge in a 40 S&W.

[MLP]

Hi Dean,

Thank you for the kind comment, and taking the time to shed some additional light on the test you did!

Hey!, thanks for the idea… the reason I was delayed in responding to this was that I was running all over TGZ addressing that issue! I appreciate the input, and have acted on it.

I am glad that I was able to give you an idea on a way increase the effectiveness of your site. Which is already quite good from what I have had the time to browse through. I understand how time consuming it is to put together and maintain a good website and moderate bulletin boards.

BTW, upon information and belief, the extractor is the spring.

Noted! I do know that the 1911A1 models use a long one piece spring steel type extractor. However, for some reason I was under impression the S&W used a short one, activated by a spring. Guess my lack of knowledge of the internal workings of S&W's is showing. However, I am always trying to expand my knowledge along these lines.

Thanks again for the additional input. I think we agree that while shooting a 40S&W in a 10mm may work in some guns, overall it is not a wise choice of things to do.

Thanks for the invite… I administer four BBs elsewhere so I don't get over here too often. Usually it's because someone tips me to a particular thread and asks for some specific input.

Well I know you stay busy with that. I administrated one and moderated two others for a while. Kept me quite busy and left me with very little spare time.

Thanks again for taking the time to drop by this board and add your input. It was very much appreciated.

As for New Years, I think I am staying home again this year. Much safer that way!

__________________
Keep It In The 10 Ring,
Michael

"Integrity is what you do when no one is looking."

[MLP]

B9mmHP,

You seem to have missed what I was Q'ing. Again this time with bold print added to what I was in reference.

It may hold the cartridge tight to the boltface, but it just pulls the cartridge away from where it should have contact in or at the bore,so you still have a dangerous situation.

Exclude rimmed cases from what I am about to say and assume that the proper cartridge is being chambered.

In any common weapon that is in proper operating condition; when the chamber is closed the headspacing surface will push the cartridge back to a point that the extractor will snap into the extractor groove and pull the cartridge back just a bit more. Thus, holding the case head tightly against the breechface and just a bit off the headspacing surface. An extractor in good condition will hold it securely there, so secure that it will pull the expanded case out of the chamber after firing.
Now in holding it securely under the extractor, as pretty much every weapon of this design does, it in effect, pulls the cartridge back off the headspacing surface.
So every time you pull the trigger on a chambered rimless cartridge, that headspaces off the shoulder or the case mouth, it is not in contact with the headspacing surface.

Above you said that this is a dangerous situation. I was just wondering why or how you feel this is a dangerous situation? Since it is pretty much the norm.

That is all I was saying or questioning.



If the extractor is so weak or worn as it fails hold the proper cartridge in place while the firing pins strikes the primer, I doubt it would reliably extract the fired case every time. Then this would be a weapon in need of repair and not one to measure other weapons against.

Actually the 308 in a 30-06 is a good example where this would be a dangerous situation. Both of these cartridges have the same case diameter and even though the rim thickness is 0.005" more on the 308, it can be chambered in a 30-06 and held in place by the extractor. Which is what happens when you chamber the 30-06 cartridge as well. However, the 308 in this instance (being it is about ½" shorter) would be nowhere close to the headspacing surface or even anywhere near reaching the rifling. This creates a dangerous situation. However, with the proper cartridge where there are only a few thousandths between the case and the headspacing surface, I see little danger.

As for the 308/30-06 maybe that wasn`t a good thought, but since it was brought up. You don`t want to fire a 270 cartridge in a 7mm eather, like not shooting a 10mm cartridge in a 40 S&W.

BTW, a 10mm will not chamber in a 40S&W as the case is too long to allow the action to close into battery.

Sorry, I realize you probably meant that the other way around, just couldn't resist poking a little fun!

Happy New Years

__________________
Keep It In The 10 Ring,
Michael

"Be civil to all; sociable to many; familiar with few; friend to one; enemy to none." - Benjamin Franklin

[sw627pc]

MLP,

Well your .308 and .30-06 would present a problem only in a rifle that utilized a positive feed system (ala Mauser) where the rim feeds up under the extractor as the cartridge is stripped from the mag. If it was the more common (now days) snap over feed the case is short enough that the extractor for a 30-06 would never engage a .308 case head. In this instance, unless you have an unusually long firing pin I doubt that the round would ever fire. Now some of the other instances you mention could present a problem. Most semi-auto pistols DO use positive feeding so this can present a serious problem with them.

Totally irrelevant, but many years ago when I worked for a sporting goods store we had a customer ka-boom a brand new rifle. Rifle and ammo from the same maker, both marked .270 Win. Upon examination of the remaining rounds in the box of 20 we found three with .284 bullets loaded into .270 cases. Maker replaced the rifle (with an upgraded one) and furnished the shooter with a CASE of ammo. Also recalled that entire lot of ammo.

[MLP]

Hi Bob (sw627pc),

Yes, I agree, and was only using the example that B9mmHP to build a hypothetical situation for what I would consider to be a dangerous situation.

A .284/7mm bullet in a .270 Win case!! Man I hate it when that happens!!
It is a good thing he was not seriously injured! I would have to imagine that it was at least difficult to close the bolt on that round in that gun. However, a person not real savvy on guns probably would not realize there was a problem with that extra effort required to close the bolt that one time. And as we both know, it would only take that one time to Kb that rifle. It is good that the manufacturer replaced his rifle, and an upgraded one was the least they could have done.

Have a Safe New Years!
__________________
Keep It In The 10 Ring,
Michael

[I]"We find comfort among those who agree with us - growth among those who don't."[I]