What exactly does "supported" mean with respect to the chamber?

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ace_himself

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Hello,

I was curious as to what precisely it means when a pistol is described as having say a partially, fully, etc. supported chamber.

Does it have to do with the locking mechanism? Ie. a purely blowback pistol would be an entirely unsupported chamber as such? I'm just guessing here I don't know for sure.

I appreciate your help on this.
 
I think it means the amount of the side of the case that is not enclosed by the chamber at the bottom rear section of the chamber. If you run a search im sure you will find pics comparing alot of different and popular handgun barrels.
 
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I believe unsupported chambers are chambers were there exists a small gap between the cartridge and the chamber causing under certain conditions the risk of a KABOOM. (I think that this only happens with cheap reloads and the such)
 
Pure Energy - That's it. It is not unusual for part of the case to be exposed. Usually it is part of the solid head. In not, the case can bulge where it is not supported. An extreme example is the Sten. There is no feed ramp, the entire breech of the barrel is coned for feed. If the case is not strong, with a solid head, the case will eject looking as if it has a belt - or the head can be blown off.
 
Here's a comparison between different chambers... the HK, Steyr and XD are the 'most' supported. Take note of the other chambers and how much of the case (at the 6 o'clock position) is not supported.

SupportedandNonSupportedChambers.jpg


Look at the Springfield XD40 compared to the Glock 22... notice how much more casing you can see in the Glock chamber?
 
dieguy59 said:
All Darko's pics are of .40 S+W, does the same hold true for 9mm?
Click to expand...

YES.

The chamber/ramp design is part of the HG engineering. The biggest reason for having a unsupported chamber is to aid in feeding IN THAT HG.

An unsupported chambered HG does not mean it feeds better then a properly designed fully supported HG.

If you only use SAAMI/mild reloads or toss your +P brass, an unsupported chamber is fine. If you want toasty reloads, an unsupported chamber can lead to case separation which can cause a jam at best or an exciting smoke show/injury at worse.

Jerry
 
This doesn't add anything to the above picture, but I was using this picture in one of my threads on here.

The barrels left to right are Glock 17, HK USP 9mm, Walther P99 9mm, and Steyr M9-A1. The Steyr is closest to a "fully supported" chamber, whereas the Glock is the one where (comparatively) you can see the most of the side of the casing.

comp4.jpg


The fully supported chamber thing isn't a big deal with 9mm in my opinion. Personally I prefer the Glock way of doing things. No matter how much crud builds up on the ramp, the rounds keep loading into the chamber no problem. The same cannot be said about the Steyr in my experience. You will get some fail to feeds if it starts to get really crudded up in there.

Then again, with a .40S&W, you may want a more supported chamber, especially if you are reloading (hot loads).
 
45acps are low pressure rounds and therefore support isn't much of an issue.

To understand what happens to cause a Kaboom follow this scenario: a round is fired in a Glock and that leaves a bulge in the unsupported area, the brass from this firing is reloaded, the weak (bulged) area again ends over the unsupported area, and when fired the weak area may let go.

Regards,

Richard:D
 
A regular 1911A1 has a chamber very similar to the picture of the Glock. But since the 45ACP runs at about only 18,000 to 19,000 PSI that is not really an issue. For hot 45 ACP loads there are supported chambered barrels but that means altering the frame. I use 45 Super brass which is the same size as 45ACP only thicker to take the higher pressures.
 
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