I came up with another new cartridge. I call it the 40 Deep Throat  .

I noticed my Lone Wolf 40S&W conversion barrel for my Glock 20 has a deep throat which allows the bullet to stick out further than a standard 40S&W and still chamber. I do not know if Lone Wolf made it that way on purpose, or if it is a flaw, but I like it. I can shoot 10mm loads using 40S&W brass. That is very nice for the range. I won't have to scrounge for my 10mm brass. I can just pick up any 1x fired 40S&W brass laying around.

I did a test using Horndy 180gr JHP (XTP) bullets in both a 10mm case and a 40S&W case using the same powder type, charge weight, and overall length. I did not have a chronograph, so I can't compare the velocity of both loads. Precision (group size) was slightly better using the stock Glock 20 barrel and 10mm brass, but if you wanted to shoot your G20 in competition, and not have to worry about picking up your expensive brass, the LW 40S&W conversion barrel and 40S&W brass would be close enough in performance not to make a big difference. The LW barrel was the older stainless barrel, and not the newer Alpha Wolf line. I have no idea if the Alpha Wolf 40S&W conversion barrel has a deep throat.







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Here is the target; shot at 10 meters. There are three 1" black dots that served as aiming points. Each group is 10 shots. The center one is the 40S&W brass and it looks like it only has 8, but the other two holes are in the top group. That is why it looks like a tighter group than the 10mm brass, but isn't.

Very interesting. Has anyone tried these "40 Deep Throat" loads in a regular 10mm? I have thought about this before but never had the courage to try it.

Quote from: Ten2six on February 16 2017 07:39:25 AM MST
Very interesting. Has anyone tried these "40 Deep Throat" loads in a regular 10mm? I have thought about this before but never had the courage to try it.

Yes, it will work (in a Glock 20), but they have to be fed from the magazine. You can't just drop it in a 10mm chamber.


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Thanks my_old_glock,  I have a surplus of 40 S&W brass. I am going to try some "40 DT" loads, my Delta Elite likes to throw the brass quit a ways. 

Quote from: Ten2six on February 16 2017 10:30:53 AM MST
Thanks my_old_glock,  I have a surplus of 40 S&W brass. I am going to try some "40 DT" loads, my Delta Elite likes to throw the brass quit a ways.

If your Delta Elite uses common 1911 parts, you might be able to get a 40S&W barrel for it, and hopefully the throat will be deep enough to work.

I have a Bar-Sto 40 S&W for it. It it is very accurate with standard loads. Can't wait to try your method.

USPSA shooters do the same thing starting back in the 90's with the early high capacity 1911's in 40, just to get them to feed reliably. Only we called it Long Seating.

Most of us settled on an OAL of 1.200 with 200 gr bullets at around 925 f.p.s. for gaming purposes but we quickly realized we could approach 10mm ballistics with most brands of brass.  Seeing Power Factors of 215-220 on the chrono stage was not uncommon back in the day.  I still have a well used throating reamer in my tool box for modifying chamber throats to accept an OAL that long.

Jeff

wondering if so little is in the case for the taper crimp to hold, would there be the possiblility of a set-back issue?

Quote from: tommac919 on February 17 2017 11:07:22 AM MST
wondering if so little is in the case for the taper crimp to hold, would there be the possiblility of a set-back issue?

For the 180 grain XTP, the bullet is 0.231" in the case.


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I thought that 1911's depended on the forward end of the case encountering the reduced radius in the barrel and resulting in the proper headspacing of the rear of the cartridge properly wrt the "firewall" surface that surrounds the firing pin.  So wouldn't the shorter case slide too far into the chamber, and produce an excessive gap between the rear of the case and the "firewall" surface of the slide?

Quote from: tommac919 on February 17 2017 11:07:22 AM MST
wondering if so little is in the case for the taper crimp to hold, would there be the possiblility of a set-back issue?

A crimp die should NEVER be used to hold a bullet in.

Quote from: gandog56 on February 18 2017 08:06:55 PM MST

Quote from: tommac919 on February 17 2017 11:07:22 AM MST
wondering if so little is in the case for the taper crimp to hold, would there be the possiblility of a set-back issue?

A crimp die should NEVER be used to hold a bullet in.

This. Factory taper crimp is VERY important for 10mm feeding in many platforms. It's for feeding.

Quote from: Mike_Fontenot on February 18 2017 05:15:05 PM MST
I thought that 1911's depended on the forward end of the case encountering the reduced radius in the barrel and resulting in the proper headspacing of the rear of the cartridge properly wrt the "firewall" surface that surrounds the firing pin.  So wouldn't the shorter case slide too far into the chamber, and produce an excessive gap between the rear of the case and the "firewall" surface of the slide?

Not if you use a 40S&W conversion barrel.

They will also work in a 10mm chambered barrel as long as the extractor grabs the case as it is feeding into the chamber. If it doesn't than the 40S&W case will slide into the chamber and not fire. It works in a Glock 20. A lot of people shoot 40S&W out of their stock Glock 20 10mm barrel without problems, but it should only be done for practice or in an emergency when you have no 10mm available.




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Quote from: Mike_Fontenot on February 18 2017 05:15:05 PM MST
I thought that 1911's depended on the forward end of the case encountering the reduced radius in the barrel and resulting in the proper headspacing of the rear of the cartridge properly wrt the "firewall" surface that surrounds the firing pin.  So wouldn't the shorter case slide too far into the chamber, and produce an excessive gap between the rear of the case and the "firewall" surface of the slide?

That is the theory however, I recall articles written in the late 1970's detailing how in autoloading pistol calibers like the 45 acp and 9mm Luger, the cases grow shorter the more times you reload them and that they actually headspace on the extractor.

That is why almost every 10mm autoloading pistol can shoot the shorter 40 S&W in a pinch. 
However, what we're talking about here is using a 40 S&W chambered barrel and 40 ammo seated out to 10mm length.