What is an unsupported chamber - 10mm ?


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Zerstoerer
August 2, 2012, 07:36 PM
Came across this statement on the CTD website:
Surprised me, that the Colt Delta Elite is on the list.
What is an unsupported chamber and is the EAA Witness also?
Beretta makes a 10mm?

"BVAC 10mm Auto Ammunition Notice:
Due to numerous customer request for the BVAC 10MM to reach maximum velocity, BVAC had changed the load to 1250 fps January 1st 2012 to March 1st 2012. In doing so, we have seen signs of case failures in unsupported chambered weapons. One example is the Colt Delta Elite. We recommend that if you purchased the BVAC 10MM ammunition during this time period that you only shoot the ammo in fully supported weapons such as the Smith and Wesson, Beretta, or Sig Sauer. You can also contact BVAC directly to exchange the ammo for the standard 10mm Auto round. BVAC has reduced the load back to the standard velocity of 1125 fps."

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Mobuck
August 2, 2012, 08:46 PM
Unsupported chamber: part of the lower rear part of the gun's chamber is cut away or relieved to improve feeding.
I once had an older Star B that came from some unknown South American police force. About the 3rd shot, I experienced a case blow out which destroyed the grips, the magazine, and would have injured me if I hadn't been wearing leather gloves. After a cleanup and another mag, I started checking the fired cases. Each and every one showed a bulge in front of the extractor groove. Removing the barrel and inspecting more thoroughly than I had the first time revealed that "someone" had ground out the lower part of the chamber almost 1/2 the length of a 9mm case.
During test firing of a S&W 6906 a while back, we had a case blow out but not as spectacular-it only blew the floorplate off the mag.
I can see that the high pressure of the 10mm would cause problems with such a setup.

Hunter125
August 2, 2012, 09:28 PM
Google supported vs unsupported chamber pictures.

Zerstoerer
August 2, 2012, 10:28 PM
Thanks for the replies.
Just surprised me that the Colt Delta Elite has the same 'problem'.
Is this just in 10mm or in any .45 Colt 1911?

Have not had any problems, but now I am almost worried.
Does the EAA Witness have an unsupported chamber also?

Hunter125
August 3, 2012, 08:36 AM
I know Glocks have unsupported chambers in .40. I'm not sure about others, but I would assume it's part of the Glock design for reliability sake for all calibers.
Part of why I chose XD.

flightsimmer
August 3, 2012, 08:50 AM
This one is almost fully supported and it is from a Colt Delta Elite. I've never had any problems with any of them including my hot handloads.

http://i366.photobucket.com/albums/oo106/flightsimmer_2009/PA280001.jpg

ATLDave
August 3, 2012, 10:18 AM
Have not had any problems, but now I am almost worried.
Does the EAA Witness have an unsupported chamber also?

Mine looks fully supported to me.

crestoncowboy
August 3, 2012, 11:12 AM
Just don't shoot bvac until they ditch armscor brass, look at my other threads for more info.

intercooler
August 3, 2012, 12:01 PM
Kimber is really good:

http://sphotos-a.xx.fbcdn.net/hphotos-ash4/376260_417438601627511_483141763_n.jpg

1006 is really good:

http://sphotos-b.xx.fbcdn.net/hphotos-ash3/s720x720/574751_417434138294624_1613917411_n.jpg

Colt Delta left isn't but Dan Wesson right is:

http://sphotos-a.xx.fbcdn.net/hphotos-prn1/s720x720/528347_417434484961256_107247788_n.jpg

Older Glock left isn't... aftermarket Glock middle is and Delta right isn't:

http://sphotos-b.xx.fbcdn.net/hphotos-ash3/s720x720/564036_417439208294117_967176743_n.jpg

intercooler
August 3, 2012, 12:04 PM
And of course my Witness guns are:

http://sphotos-b.xx.fbcdn.net/hphotos-prn1/s720x720/528820_417438084960896_219795920_n.jpg

ATLDave
August 3, 2012, 12:22 PM
Great pictures, Intercooler! When you look at the amount of brass left to fend for itself in the Colt pictures, it makes me wonder how they don't blow out the brass 100% of the time!

243winxb
August 3, 2012, 12:24 PM
Dont load hot & they wont bulge. :) http://i338.photobucket.com/albums/n420/joe1944usa/Firearms%20%20and%20%20Reloading/40Support.jpg

balance 740
August 3, 2012, 01:29 PM
Early Glock 20 pistols had unsupported chambers.

http://www.ar15.com/forums/t_1_5/1253136_My_10mm_KaBoom.html

There are pictures in that thread that show the changes Glock made to their Glock 20 barrel designs over the years.

StrutStopper
August 3, 2012, 02:00 PM
Thanks for the replies.
Just surprised me that the Colt Delta Elite has the same 'problem'.
Is this just in 10mm or in any .45 Colt 1911?

Have not had any problems, but now I am almost worried.
Does the EAA Witness have an unsupported chamber also?
I'm not sure about "any .45 Colt 1911", but it shouldn't make a difference in .45. The problem with unsupported chambers is generally with higher pressure rounds like .40 and 10mm. I think you'd be hard pressed to find a .45 ACP round (at least factory loaded) that would cause a KB.

Skylerbone
August 3, 2012, 08:39 PM
Don't under estimate any firearm and the potential for disaster: http://forums.1911forum.com/showthread.php?t=375084. Somewhere in that thread is a link to another 1911 that detonated and looked far worse.

Colt's 10mm has a long history of problems, the .45 not so much.

Zerstoerer
August 4, 2012, 02:10 AM
Great pics and info, thanks to all.

horsemen61
January 22, 2014, 02:57 PM
thanks for the info guys

critter
January 22, 2014, 03:40 PM
I had a Colt DE blow a case. Blew out the magazine-little other harm. Too much unsupported for the amount of pressure if you try to get a lot of hoursepower out of the 10 mm.

Not enough margin of error for me. Sold it to somebody who wanted it much worse than I did.

The .45 ACP is often unsupported in a 1911-type BUT it operates at low enough chamber pressure that it works ok.

el Godfather
January 22, 2014, 05:13 PM
What load you fired?

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