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

[44MAG#1]

What was missed that would make the ammo of a 40 firing in a 10 the case has to headspace on something. IT CANNOT BE ON THE FRONT OF THE CHAMBER. PERIOD.
So that leaves the extractor.

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]

Any case that stops in the barrel five thou below the hood is definitely not headspacing on the extractor. Thanks for the dimension measurement and the third party confirmation.

Anyone else care to check using the right ammo in the right chamber? It will take just a little time to see.

And no, what ever is happening is not extractor headspacing. I see I am gonna have to spell this one out.

[35remington]

No one is questioning whether a 40 case will headspace on the extractor in 10mm. What is being discussed is whether proper ammo in the proper chamber headspaces on the extractor.

I think people get this wrong because they measure the wrong things.

[44MAG#1]

Any case that stops in the barrel five thou below the hood is definitely not headspacing on the extractor. Thanks for the dimension measurement and the third party confirmation.

Anyone else care to check using the right ammo in the right chamber? It will take just a little time to see.

And no, what ever is happening is not extractor headspacing. I see I am gonna have to spell this one out.

I did not say that I said the case was .005" below the barrel hood while in the extractor. That is it just dropped into the barrel and then measured.
You are grasping at straws.
THERE IS A SNUG FIT OF THE CASE IN THE EXTRACTOR. NO MOVEMENT FORE AND AFT PERIOD.

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]

Thanks for absolutely confirming your 10mm case in your 10mm chamber is not headspacing on the extractor. Case mouth headspacing is what it is doing. I understand you just dropped it in the barrel. I am not grasping at straws.

Anyone else?

[35remington]

I think at this point you really need to ask me how I know that.

[44MAG#1]

Thanks for absolutely confirming your 10mm case in your 10mm chamber is not headspacing on the extractor. Case mouth headspacing is what it is doing.

Anyone else?

First off I never said either way. You are grasping at straws. The extractor holds the case tight against the breech face.
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]

I think at this point you really need to ask me how I know that.

You dont know that.

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]

Ah....finally we hit the point of contention, which is how people get this wrong.

“The extractor holds the case tight against the breechface.”

No, it does not. I’m afraid pictures are in order. Remember the contentious point is about proper ammo in proper chambers

[44MAG#1]

Ah....finally we hit the point of contention, which is how people get this wrong.

“The extractor holds the case tight against the breechface.”

No, it does not. I’m afraid pictures are in order. Remember the contentious point is about proper ammo in proper chambers

I dont have to provide photos etc. to you or anyone else.
I dont care. I am telling you what I have found and what is going on. Take it or leave it.

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]

No need to provide photos. I will, and it will clearly make my point. Stay tuned. This will show you that something other than what you think is going on.

[Texas by God]

Since the shorter case cannot headspace on the chamber mouth the headspace measurement is essentially moved to the front of the rim. If headspace is required for a cartridge to fire, this is what is happening. The extractor holds the case rim tight while the chamber walls provide stability, providing all that is required for ignition. I could shoot .380 ACP, 9mm Luger, 9mm Steyr, 9x21 and .38 Super in my Astra 400. I shot a LOT of 9mm Luger in it with no ill effects. Back to the OP, yes you can shoot .40 S&W in a 10mm and all you'll get for certain is a dirty chamber.

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[44MAG#1]

Since the shorter case cannot headspace on the chamber mouth the headspace measurement is essentially moved to the front of the rim. If headspace is required for a cartridge to fire, this is what is happening. The extractor holds the case rim tight while the chamber walls provide stability, providing all that is required for ignition. I could shoot .380 ACP, 9mm Luger, 9mm Steyr, 9x21 and .38 Super in my Astra 400. I shot a LOT of 9mm Luger in it with no ill effects. Back to the OP, yes you can shoot .40 S&W in a 10mm and all you'll get for certain is a dirty chamber.


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Amen. Who cares about the minute details? I sure dont. Some do to have fulfilment.

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.

[cwlongshot]

[35remington]

Does the extractor hold the case tight against the breech?

No. It can’t. If it did the gun would not feed. It has to allow the case rim to wander quite a ways forward of the breech before stopping its forward movement.

By actual measurement, the case head is forward of the breechface in the photo of the M and P 40 below by 30 to 33 thousandths of an inch. Other guns of various makes have similar gaps. They have to or they would not feed.

Most pistols these days have tight hood to breech tolerances, but even given a few thou clearance allowed, 44’s cases would have to be at least 20 to 25 thou shorter than they currently are to headspace on the extractor. Unless they were deliberately trimmed very short....you won’t find any that short.

44’s 10mm cases in his 10mm chamber are pretty clearly headspacing on the case mouth.



Sorry it is a bit blurry, but the noticeable gap between case head and breech is pretty evident.

[35remington]

2nd try

[35remington]

At this point, those that maintain that correct ammo used in correct chambers regularly headspaces on the extractor have a little wind taken out of their sails, I would guess.

[35remington]

I would be quite happy to show a similar photo on the other makes of guns that I have.

[35remington]

Incidentally, the 1911 has a wider gap of 40 to 43 thou. Again, the gap cannot be substantially smaller than that shown or the gun would be a jammomatic.

[44MAG#1]

Try a Glock.

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.