Glock unsupported chamber

[rlewpolar]

Can anyone explain to me the concept of Glock's unsupported chamber. When reloading, I'm coming across bulged brass and the explanation is Glock's unsupported chamber but not sure what this means and haven't heard a good explanation. Thanks.


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[ojisan]

Look carefully at this pic:


The barrel on the right has a much deeper feed ramp than the one on the left.
This promotes feed reliability but does not fully enclose (support) the case head and web area.
The barrel on the left is considered to be fully supporting the case head and web area.
The exposed web / side portion of the case is where the barrel on the right will cause the bulge to appear.

Any fool can make a feed ramp that is deep and wide that will feed reliably.
The trick is to make the gun feed reliably while still supporting the case head.

[Carcassonne]

Can anyone explain to me the concept of Glock's unsupported chamber. When reloading, I'm coming across bulged brass and the explanation is Glock's unsupported chamber but not sure what this means and haven't heard a good explanation. Thanks.


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Glock's feed ramp is partially in the barrel chamber. With high pressure ammo, you will get a bulge. Bulges are cause by over pressure ammo, not poorly designed barrels. S&W Shield pistols in 40S&W also cause the brass to bulge.



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[rlewpolar]

Excellent, thanks for the explanations. That pic clarified it for me [emoji106]


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[trackcage]

So why does everyone rave about the glock 20 (10mm)? Seems like that would be THE prime candidate for bulged brass

[TruEdge]

Ive had that happen out of a glock 17 using some reloads from redline ballistics. Happened consecutive times but then when we switched to factory ammo everything was a ok. Using the same redline ballistics ammo but this time .40 out of a G22 no issues. Probably around 700 rounds of it with no issue actually.

[justjeff]

So why does everyone rave about the glock 20 (10mm)? Seems like that would be THE prime candidate for bulged brass

Some reloaders run the "glocked" brass through a die (bulge buster) to remove the bulge

Some Glock 10mm shooters buy a supported chamber barrel (I bought one for my 21sf to swap to 10mm)

Some Glock 10mm shooters don't shoot high pressure loads

[Snoopy47]

Reloading brass shot out of a factory Glock barrel can be a little more challenging.

It takes a little more muscle when going through the sizing die.

Even more annoying is using brass shot out of a factory barrel Glock in something other than a Glock.

A great solution is of course an aftermarket rifled barrel for the Glock, however feeding reliability goes down dramatically.

Glocks are designed as a combat pistol to shoot never fired factory ammo, and not as a hobby shooter/reloader's pistol.

That's not to say they couldn't be made to be so. I'm not a Glock guy, but play around with it, and soon enough you'll have dialed in your Glock for your reloads.

At the very least, you HAVE TO resize the brass with a sizing die.

[rlewpolar]

Glock unsupported chamber

Yeah, I use Lee dies and the crimping die (last die in the process) removes the bulge. But I don't have a Glock so no clue whether they will work ok in the Glock. I do use these resized bulged cases in other pistols and they work perfectly. Hmmm, was contemplating buying a 10mm Glock and reloading for it but this makes me pause.


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[trackcage]

Hmmm, was contemplating buying a 10mm Glock and reloading for it but this makes me pause.


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Me too, that's why I asked. I actually wanted to load up hot loads too. So an aftermarket barrel is what it would take?

Do I really need a special die to remove the bulge? I couldn't just full length resize (even if it takes some serious effort)

[bountyhunter]

Do I really need a special die to remove the bulge? I couldn't just full length resize (even if it takes some serious effort)

I think that works. I used to shoot tons of commercial .40 reload and they bought fired police brass that went through Glocks. Any straight walled case should size up fine it's tapered cases like 9mm that cause problems with the infamous bulge.

[ojisan]

Lee Bulge Buster link. There are other bulge remover tools available.
Note Lee's comments on resizing bulged Glock brass.

http://leeprecision.com/bulge-buster-kit.html

Cliff notes:
- The brass gets thinner where it has been stretched into the bulge shape.
- Resizing the brass does not put the metal back into the thinned area.
(The case has been permanently weakened).

When loading hot for any caliber, I only use new or once / twice fired, never-bulged brass.


Good thread here, too:

http://www.calguns.net/calgunforum/archive/index.php/t-871339.html

[bountyhunter]

When loading hot for any caliber, I only use new or once / twice fired, never-bulged brass.

Very good advice. My old reloader only used once fired cop brass.

[Carcassonne]

So why does everyone rave about the Glock 20 (10mm)? Seems like that would be THE prime candidate for bulged brass

The max SAAMI pressure of the 10mm cartridge is 37,500 PSI (1,000 PSI less than 9mm +P). The max SAAMI pressure of the 40S&W cartridge is 35,000 PSI (2,500 less than 10mm). Neither the longer length nor the 2,500 PSI higher pressure of the 10mm compared to the 40S&W makes a difference in case bulge. Case bulge is caused by people loading the cartridge above SAAMI pressure specifications.



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[stormvet]

I reload tons of Glock fired 9, 40 and 45. I do not get bulged brass and use the casings many many times. I use a standard RCBS sizing die(I resize all my brass, no matter the cartridge or gun that fired it)
Early gen 3 as well as gen's 1 & 2 have less support, Glock tightened it up with the later 3's and 4's. Glocks have looser chamber fit then most other guns( hence one of the reasons they are so reliable)this can also lead to a bulge.
When I find bulged casings, as long as everything else is fine with the casing, I just resize it and load away.
In my 25 years plus reloading, I've never had an issue with them.