Shooting 40 S&W in a 10mm Semi Auto?

[Lloyd Smale]

hammer hammer!

And you really hammered your view point home at the end of post #24:

Lloyd wrote : "yup that's the real problem with doing it over the long haul. Ive done it in my 22 glock and it worked fine. But plan on using a wire brush on your chamber every time you do it and even then if your talking 10k rounds your going to probably end up with a rough chamber. As to extractor were or headspacing ill say this. Realisticaly all semi autos headspace on the extractor. If you loaded 10mm so that it actually head spaced on the rim it wouldn't take many rounds to gum the gun up and reduce reliability. Youd also have to trim brass regularly and I can honestly say I haven't trimmed handgun brass in 30 years. My guess is 99.9 percent of the ammo that goes through semi autos doesn't have the rim touching a thing. "

So yes, I agree that you never explicitly stated that you believe the guns are designed to headspace on the extractor but you sure did make your opinion on the importance of the extractor a key point in the expression of your views.

[Sig556r]

SAAMI and the reloading manuals all say it headspace on the mouth, but apparently the people who chamber barrels do not agree. You will note that the headspace gauge pictured below does not have a case mouth. My experience in loading for the round since the mid-90's is that the barrel makers headspace it off the shoulder, and I actually had to grind the bottom off my RCBS sizing die so it would set the shoulder back far enough for my reloads to chamber in more than one 357 barrel.

In deference your statement, I don't think Sig Sauer (I have them in 1911 nightmare, P229 & P226) chamber their barrels contrary to their design of the round. Not saying it can't headspace on the shoulder either, but that ain't the design intent. I too have loaded the round successfully but haven't got the need to grind my dies.

[Lloyd Smale]

Do you measure out and perfectly trim brass in all your handguns after every shooting? If you do then judge me. But if you say yes its pretty obvious you spend much more time loading then actually shooting. Do you keep separate ammo for multiple guns in the same caliber? Ive got better things to do. I don't weight out every charge or clean primer pockets either. Shame on me. Me? id rather be shooting. Check seating dept with either a case gauge or plunk test in my tightest gun when I first loading and crank up the Dillon or lnl and fill a couple coffee cans and go shooting. Id have to be awful bored to trim handgun brass clean primer pockets or sort bullets by weight and as long as I can shoot I just don't get that bored. Aint my first rodeo. Ive been loading for 40 years and kind of think ive got a pretty good grasp after a few million rounds of handgun ammo what works and what doesn't and whats necessary and whats a waste of time. Local sheriffs dept uses 1000s if rounds of my ammo in there guns for practice and ive never heard a complaint by them either.

The troubling part is suggesting that this all can be resolved if some measuring was done, yet that person is absolutely determined not to measure anything. Opinion is a poor substitute for knowledge. It is possible to really not want to know how things work.

[35remington]

Lloyd, if you want to know, start measuring. If you want to be in error, don’t.

It is just that simple. I have done what is needed to answer the question correctly.

[Petrol & Powder]

Lloyd, can you share with us exactly how you believe a rimless cartridge headspaces in a semi-auto pistol?

[marek313]

Long thread in a long line of can you shoot 40S&W in 10auto. I was asking the same question not too long ago. After doing my research online I decided to give this a shot and shoot 40S&W in my 10mm RIA 1911. I cant vouch for other guns but I have no problems at all. I do seat my 40s little long to close up the gap but so far so good after probably 500 rounds of 40S&W mixed in with 1K of 10mm. I keep my 10mm brass for medium to hot loads and shoot 40s for a nice soft round. Havent had any problems with my extractor or anything else yet knock on wood

[Lloyd Smale]

pretty simple they don't headspace. The extractor keeps the round from going to far forward and having misfires due to light primer strikes.

Lloyd, can you share with us exactly how you believe a rimless cartridge headspaces in a semi-auto pistol?

[Lloyd Smale]

Lloyd, if you want to know, start measuring. If you want to be in error, don’t.

It is just that simple. I have done what is needed to answer the question correctly.

You never answered if you measure and trim every piece of pistol brass and trim it exactly to fit each individual gun and do it every firing. If you do your probably in the maybe one percent that do. plain and simple if your not doing it your not heaspacing on the rim of your round. Answer me this. If you trim your brass to minimum lengths given in a loading manual and your gun is a bit generous in its chamber what ARE YOU headspacing on? Do you really think every manufacture of every 9mm pistol made uses the exact same chamber reamer or even when one wears out use another EXACTLY like the first? Head spacing on the extractor might technically not be the proper term. Technically we as handloaders and even gun and ammo manufactures don't concern ourselves with headspace in handguns. they don't have a shoulder that might get fire formed so much that it fatigues brass like a bottle neck round might or cause a catastrophic case failure. So call it what you want. Load the way you want. But I know my guns go bang every time I pull the trigger and the rim doesn't have to contact a thing in that process.

[Petrol & Powder]

pretty simple they don't headspace. The extractor keeps the round from going to far forward and having misfires due to light primer strikes.

So, Lloyd, you're going on the record and saying that rimless casings such as the 9mm and 40 S&W,.....DON'T HEADSPACE ?

You're saying that sharp ledge at the forward end of the chamber has nothing to do with head space ?

You're saying that if one were to remove the extractor and chamber a live round, that round wouldn't fire? Is that what you're saying, Lloyd?

[marek313]

So, Lloyd, you're going on the record and saying that rimless casings such as the 9mm and 40 S&W,.....DON'T HEADSPACE ?

You're saying that sharp ledge at the forward end of the chamber has nothing to do with head space ?

You're saying that if one were to remove the extractor and chamber a live round, that round wouldn't fire? Is that what you're saying, Lloyd?

I think what hes saying that even though rimless casings are designed to headspace on the case mouth there are many short cases (Hornady comes to mind) where in fact case headspaces on the extractor and case mouth never touches the chamber. I dont know how often thats actually the case but I've heard few people make that claim now. If you keep breaking extractors i would definitely look into this but most guns and most brass thats probably very unlikely scenario. Maybe someone with more know how could do some research into that.

[Elkins45]

So, Lloyd, you're going on the record and saying that rimless casings such as the 9mm and 40 S&W,.....DON'T HEADSPACE ?

You're saying that sharp ledge at the forward end of the chamber has nothing to do with head space ?

You're saying that if one were to remove the extractor and chamber a live round, that round wouldn't fire? Is that what you're saying, Lloyd?

I don’t presume to speak for Lloyd but what I take him to mean is that the extractor provides sort of a “pseudoheadspace” by preventing a short case from going so deeply into the chamber that it contacts the ledge. Without the extractor the round probably won’t fire, especially if tilted down. It might be more likely to if held straight up.

I wonder if it would fire if you removed the barrel, shoved a round under the extractor and dropped the hammer? I’m not crazy enough to try this, but it could probably be safely tested with an empty primed case...although the heavy bullet probably provides some inertia to help the case stay put long enough for the firing pin to fully dent the primer.

[35remington]

Lloyd, I do not trim autoloading pistol brass.

Once again you are making a contradictory argument and you do not realize it. The first few sentences of post 68 are just that.

If a case is not trimmed, it is extremely unlikely to headspace on the extractor, because it will not be as short as possibly excessively trimmed brass. Hardly anybody trims autoloading pistol brass including, by your own admission, yourself. Your implication that longer untrimmed brass is more likely to be headspaced on the extractor speaks volumes, in that it makes it clear you do not have a very good grasp of the technical details of this topic and are thus ill equipped to discuss it.

Which, I suppose, explains the viewpoint that you have.

What is remarkable is how you are assuring me how everything works, yet you don’t bother to measure or check to see if your assertion holds any water or not. As I said, I measured the fit of my untrimmed, unaltered brass in my pistols. It isn’t headspacing on the extractor.

Manufacturers of firearms are members of SAAMI, as are ammunition makers. They are required as members of that organization to hold chambers and ammo within tolerances, and it is no surprise that they do. These tolerances in actual use see to it that headspacing on the case mouth is by far the most common situation.

What is also remarkable is how many people assume manufacturers cut chambers extra generously deep (the heck with SAAMI specs, apparently).....yet have never measured actual chambers to see if it is occurring.

Lloyd, this has pretty much run its course. What I am getting from your replies is you want to talk about theoretical things and make assumptions based on not actually finding out if they actually occur or not.

As for myself, this knowledge I have came about from reading and hearing about all the individuals on the net and elsewhere that repeated what they heard. When I asked if they had checked to see if this supposed extractor headspacing was occurring, most eventually admitted they had not, just as with your situation. None of those that had not had the faintest idea even how to determine if it was happening.

That sure didn’t prevent them from trying to speak knowledgeably about a topic that they had no knowledge of, or had any interest or ability to resolve correctly. This seems to be all too common, and such conversations find that individual defensively trying to steer the conversation toward what is believed rather than what is actually known by investigating.

Resolving the issue isn’t hard. But if you just don’t want to know, it would save a lot of print by saying that right up front. I can speak of exact clearances, technical data, and why I formulated ny understanding of how all this works, but the audience has to have an open mind, and the ability to realize that actually measuring beats theorizing about something they are clearly unsure about.

[35remington]

An offer I can make is that for those with an open mind I can show, with pictures, exactly how all this is determined. Rocket science it ain’t.

[Petrol & Powder]

I think what hes saying that even though rimless casings are designed to headspace on the case mouth there are many short cases (Hornady comes to mind) where in fact case headspaces on the extractor and case mouth never touches the chamber. I dont know how often thats actually the case but I've heard few people make that claim now. If you keep breaking extractors i would definitely look into this but most guns and most brass thats probably very unlikely scenario. Maybe someone with more know how could do some research into that.

Thank You, I'd like to hear what Lloyd has to say.

[35remington]

The problem is.....how short does a case have to be to headspace on the extractor?

If you haven’t measured you have no idea. If you have, you do. One situation is clearly more useful than the other.

Here’s a hint.....much shorter than you probably think. Which is why it is a quite rare occurrence.

[44MAG#1]

Speaking only, speaking only, only speaking of MY Glock M20. A Starline case when slipped uner the EXTRACTOR has NO detectable movement fore and aft. In fact it fit quite snugly. Still the gun functions with no problems.
Now with the case dropped into the chamber the head is not quite even with the barrel hood. The case sets very, very, very, very close to .005" under the barrel hood.
Now with that, even though Lloyd may not be technically correct for the number crunchers, he is correct, at least concerning my Glock M20 load her up and shoot the thing.


Again I mean no hurt, harm, anguish or turmoil by my post I have posted on this posted subject. I am not baiting, trolling or calling out anyone. I am making a post based on my experience, knowledge and/or belief or opinion. That is all.

[44MAG#1]

Speaking only, speaking only, only speaking of MY Glock M29. A Starline case when slipped uner the EXTRACTOR has NO detectable movement fore and aft. In fact it fit quite snugly. Still the gun functions with no problems.
Now with the case dropped into the chamber the head is not quite even with the barrel hood. The case sets very, very, very, very close to .005" under the barrel hood.
Now with that, even though Lloyd may not be technically correct for the number crunchers, he is correct, at least concerning my Glock M29 load her up and shoot the thing.
Now this is with MY two Glock 10MM's.
Have not checked my Ruger 10MM 1911. Probably wont.


Again I mean no hurt, harm, anguish or turmoil by my post I have posted on this posted subject. I am not baiting, trolling or calling out anyone. I am making a post based on my experience, knowledge and/or belief or opinion. That is all.

[35remington]

44 is this using a 10mm case? If it is the numbers make sense. If it is for a 40 case this may be reason for me to spell out how to check, for something obvious was missed.

In that instance I get the impression this is not being assessed correctly. I would guess most do not know what to look for.

[44MAG#1]

44 is this using a 10mm case? If it is the numbers make sense.

Yes it is.


Again I mean no hurt, harm, anguish or turmoil by my post I have posted on this posted subject. I am not baiting, trolling or calling out anyone. I am making a post based on my experience, knowledge and/or belief or opinion. That is all.

[44MAG#1]

Now before the 40 S&W case come into question while it drops much deeper into the Glock M29 the Starline 40 S&W case is a tiGHT fit between the breech face and the extractor just like the 10MM case does the 40 will headspace on the extractor. I fire 40 S&W in a 40 S&W and a 10MM in a 10MM.


Again I mean no hurt, harm, anguish or turmoil by my post I have posted on this posted subject. I am not baiting, trolling or calling out anyone. I am making a post based on my experience, knowledge and/or belief or opinion. That is all.