After making the first video of 10MM chamber support
There was a lot of questions and request for additional pistols included. After two years unfortunately I was able borrow a few pistols to fulfill the request. Your request do not fall on deaf ears and I do try to answer all of the questions.

I want to thank all of my friends for loaning me these pistols to do this evaluation. Though I might be getting the short end of the stick as I do return all pistols cleaned no matter if I fired them or not.

By the way you are going to want to stick around to the very end probably the least expected winner and ending!!!!!!
https://vimeo.com/376583270

Link is broken , cant view

Links for video 1


video 2

Great videos-- i know the internet sometimes exaggerates small issues and many times I have heard that glock has a fairly unsupported chamber, any idea where it might fall on your scale? What about rock island? Lots of guys seem to like their ria's

I know you cant do them all, but it's good info for reloaders and for prospective buyers

I have a G20SF-3 and the stock barrel has fairly good chamber support probably at middle ground in the above examination. I have 2 auxiliary barrels one a Lone Wolf 6" and a KKM 6". The LW barrel completely engulfs the cartridge with a tight chamber. The KKM has a looser chamber with a tad less surround over the feed ramp.  Cases fired in the KKM will not chamber in the LW while cases fired in my P220 will chamber in the LW.
All 4 barrels have fired set the woods on fire hunting style loads with no sign of abnormal case head expansion.
I hope I have not muddied any water.

These are G-29 barrels
Storm Lake 40S&W conversion / G-29 Factory / Storm Lake 10mm


Smith & Wesson 1006
Bar-Sto 40S&W conversion / Bar-Sto 9x25 Dillon conversion / S&W factory 10mm

Sorry about the link fellas and thank you for the assist Shadow.

Hey guys,
I read somewhere that it's the older Deltas that had the support issue and this was subsequently fixed by Colt. no?

Nope.

https://rangehot.com/case-head-support-colt-delta-elite/

IMHO, most of the "case head support problems" are handloads that are actually over pressure.  I could be wrong, but that is generally my perception.

SqlBullet,

Me and Hunter have had this debate but do come to agreement. It is more than just chamber or casehead support. The brass case web thickness also plays a very big part and believe it or not they are not all the same. But here is what I will say SAAMI spec is not the answer and this is where Hunter and I disagree. Because Buffalo Bore, Underwood, Double Tap and Fenix Ammunition all say their ammo is within SAAMI of 10MM. With most using starline brass that has a thicker case web than many others. I have witnessed serious ballooning out of those brands of ammunition in those pistols with less chamber support, to a point where I would just trash the brass as any brass with that sort of expansion is not safe to me even if you run it through a bulge buster die. My hands, fingers are worth more.

Now if you stick to major manufacturers who load at 40S&W level or just a tad hotter than 40S&W you will absolutely not have any issues.

I would agree with the argument that case web thickness plays and load level plays a large part. I would also agree that the older blued Delta Elites really didn't have a chamber support problem as I've had one since '87 or '88. As stated in the link that Sqlbullet provided, the gun will handle a proof load without a failure. Originally, I'm guessing, that was with Norma brass. Factory Norma loads were pretty hot and their brass was pretty tough.

In my own experience, before the 800X load data was changed from a 10.0gr max, I worked up to that load in my DE. 6 empties showed nothing more than slightly flattened primers. It was a handful, though. I was using new Starline brass.

In the case of the older DEs, I would agree with Sqlbullet. If one experienced a case head failure, it was probably hand loaded too hot. Perhaps more than once.

Everything is relative to the process of firing a cartridge, from chamber support, case design, whether it is stiff/less malleable or soft/malleable and it's alloy content of copper and zinc or other.
One of the issues I have seen is dwell timing and early unlock for various reasons in some firearms, especially hotter loads.  One thing I have noticed is the non-captive recoil springs can add more spring pressure at lock up.  Even though it is only a slight increase, it does add some advantage to delay the slide movement at ignition.

The further the bullet travels down the barrel, the pressures can drop off some depending on the primer and powder used.  This is where dwell timing comes into play.
I have used various brass over my years with 10mm and the older Norma & Winchester brass seemed to be better but slightly stiffer.  Hornady seemed almost too stiff and cracked lengthwise in some loadings.  Starline is very soft as new and as such it is a handloaders brass for reuse.  I have seen the primer pockets get loose with heavy loads and primers pop out.  Midway, Top Brass, Speer, JAG & Remington were a good brass.  S&B is OK for a few loadings.  Now AUSA, PPU can be questionable from new and especially as reused, we have seen it to be problematic after resizing and not holding its resized dimensions which increases the chance for bullet setback issues. This could have lead to several casehead failures in some incidents.

Handloaders need to carefully inspect their brass inside and out.  Using a single stage press can yield a better feel of things than the use of progressive press as things can go unnoticed as several things are taking place at the same time.

I think companies like Underwood, Buffalo Bore, Double Tap have made some changes to their loads and may be more inline with the pressure specs for the upper end performance.  That being said Fenix Ammo is still pushing the envelope with their 10mm offerings and as seen in some pull-downs charge weights can vary.

Be safe!