Pressure

[Bucksnort1]

Today, I was channel surfing. I came across the show, "How It's Made" and caught the tail end of the segment on a company manufacturing replica wheel guns. I don't know the manufacturer.

The last procedure is to test the guns. The announcer said this company's test rounds are loaded to pressures three times normal. Because these are replica six shooters, I'm assuming they are made to not handle higher pressures you see in modern guns with different materials and such.

Will someone address the pressure situation, perhaps how component manufacturers use this? I'm sure someone will give me a TMI response, you know, Too Much Information, so how 'bout a simple explanation.

 

[Mobuck]

I'm thinking proof ammo is loaded 20-30% over factory standard pressure NOT 300% of standard.

 

[Clark]

https://www.youtube.com/watch?v=qYOJa8ZNxmE
That is Uberti shown in How It's made.
The proof test is at 4:50 into the video.
It says, "Three times the normal operating pressure."
If that is a 45 Colt that as SAAMI registered at 14,000 psi max average pressure, then proof loads would be 1.4 to 1.55 times that or 19,600 -21,700 psi.
While 3X would be 42,000 psi
I have two Uberti Cattle revolvers in 45 Colt.
An early one with thinnest chamber wall at 0.041" between chambers.
A later one with thinnest chamber wall 0.044" between chambers
In contrast an S&W 25-2 that Clark Custom [no relation] modified for 460 Rowland for more than a decade to shoot 40 k c.u.p. ammo has 0.061" between the chambers.
Also in contrast the Ruger Blackhawk 45 Colt has 0.059" between the the chambers and often have data published at 25,000 c.u.p.

Those are the facts.
My seat of the pants guess based on blowing up the cylinders on half a dozen revolvers is that the Uberti 0.041" thick steel with .48" inside diameter cannot take 42kpsi and will blow up.

CAUTION: The following post includes loading data beyond or not covered by currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assume any liability for any damage or injury resulting from use of this information.
I have never shot anything but what Quickload thinks is 21.4 kpsi in my Uberti Cattleman 45 Colts... and the chrono data matches the QL velocity prediction.

 

[Hunter Customs]

I have two Uberti SA revolvers in 45 Colt caliber ,love both of them.
I shoot Tier Two loads in them with no problems so far, however I agree with Clark, I don't believe the Uberti revolvers will handle 42,000 PSI.

By the way Uberti guns are required to be tested by CIP standards and CIP list 45 Colt loads at 16,000 PSI where as SAAMI list 45 Colt at 14,000 PSI.
CIP requires guns to be proof tested with loads at least 30% greater then standard listed loads, so the proof load for the 45 Colt would have to be at least 20,800 PSI.

 

[Bucksnort1]

My thinking that the segment was about Uberti is apparently right.

Mobuck, I'll bet you are right. 3X seemed like a lot.

So when a gun mfg tests a handgun which has never been on the market, do they report to SAAMI or does SAAMI do their own testing?

 

[Hunter Customs]

So when a gun mfg tests a handgun which has never been on the market, do they report to SAAMI or does SAAMI do their own testing?

Unlike CIP I don't believe SAAMI requires guns to be proof tested or proof test guns, I believe they just test and set standards for cartridge pressures.

However CIP does require European gun companies that are members of CIP to proof test every firearm they manufacture.

The pressure of the proof loads has to be at least 30% greater then the standard listed CIP load.