New Glocks vs Old Glocks; Barrel Chamber Support Difference?

[REDLINE]

Seems like more and more I'm seeing some amount of consensus or general theorizing suggesting 10mm Auto Glock chamber support has been improved upon.  But of course this is the internet and I'm skeptical.  I can't tell if anyone knows from direct verification or if it's all conjecture.  Can anyone verify the 6 o'clock chamber support either way between the barrels of at least a 5 year old G20 and a brand newish G20 or G40?  Supporting close-up pictures would be great.

I remember from many years ago claims that some of the early Generation 2 G20s had really poor barrel chamber support and that it was improved on in later Generation 2 models and carried on through the Gen 3 models for as long as they've been available.  Never really knew if there was any truth to it and pictures were never posted for comparison.

It has crossed my mind that maybe there has been inconsistency with 10mm Glock barrels.  But I have NEVER seen any proof to support the thought.  If anything all Glocks seem to be very consistent with each other in the same model range.

Maybe it's all in the individual's thoughts on the dangerousness or not of a Glock Smile.  IMO a Glock Smile is never okay.  I've seen some claim it's not an issue to them.  Of course then I wonder if they actually differentiate between a Bulge without a creased Smile and a Bulge with a creased Smile.  It's hard for me to believe anyone would simply disregard a bulge with a creased smile and think it safe to keep shooting ammo doing the same.  Then again it's not hard to believe much of anything anymore.  There's only one outcome after going beyond a creased smile and that is case failure in the form of a blowout in the brass case.  This has been documented plenty over the years.  Sometimes with catastrophic failure to the firearm and sometimes not.

On a side note, one thing I would also really like to know is;  using new Starline brass in a bone-stock Gen 3 G20, what is the pressure range in PSI between a smile (the actual crease) first forming and actual case failure?  It would be really cool if pressure testing ammo was as common as chronographing ammo.

[tommac919]

snipped;
On a side note, one thing I would also really like to know is;  using new Starline brass in a bone-stock Gen 3 G20, what is the pressure range in PSI between a smile (the actual crease) first forming and actual case failure?  It would be really cool if pressure testing ammo was as common as chronographing ammo.

Don't know about the pressures, but in my stock G20-3 it can be common to see even bulges around base but not smiles...

Most of my cases end up at the .431 - .432  after firing re expansion with some of the real HOT ones at .433+. ( all new starline in hot rounds )
The only time I have seen smiles is with light weight / high speed ( like 135 gr ) heads in premium brands ... and to add,  the cases expansion was .434+
( in my opinion, they must be above safe loads ( read here pressure ) compared to what I've seen with my own )

[sqlbullet]

Not 10mm, but here are pictures from a late 90's G23 vs a 2009 G23



This shows a good bit more support by 2009.

[Ramjet]

I would venture to say the difference or increase in pressure between the "creased smile" and "bulged" case is significant and very likely boarder ing on dangerous for the shooter and gun.

[4949shooter]

No smiles on my Glocks thus far.

A 2011 Gen 3 and a Gen 4...

[Wolfie]

Great insight.

[10mmGarand]

I have a GEN3 20 made in 2009, according to serial number.

With stock barrel and RSA, approximately 20% of Underwood 200 gr. XTP's show a bulge, and 10% show a creased smile.

It looks about like the photo of the 2009 G23, but I don't have any newer Glock 20 factory barrels to compare chamber support

[REDLINE]

That's a night and day difference between the late 90's G23 and 2009 G23!  Thanks for the pic.  I wonder if 2015 G23 barrels are any different.

Hopefully someone can post a pic comparing two actual 10mm Auto Glock barrels.

[The_Shadow]

The 10mm Glock chambers are right at 0.434", so the higher pressure rounds will expand to fill the chamber, any thing more is the beginning of the smiled casing.

I will say not all brass is the same malleability.  Star Line is left softer for handloading purposes, being more malleable it will expand to fill the chambers.  This changes as the brass is being worked/resized and becomes stiffer with reuse.

[sqlbullet]

Makes me think I should shoot all my brass the first time or two in my Witness guns which have tight chambers to harden up the brass a bit.  Then run it in my Glocks.

As I recall, Swamp Fox used to say he preferred once fired starline brass for the hottest loads.

[REDLINE]

Star Line is left softer...

I wish all cartridge brass case manufacturers labeled their brass by some sort of universal hardness scale like the Brinell Hardness Number for lead.