Barrel proofing

[WestKentucky]

I need some help understanding the modern method of proofing a barrel...or if people/companies even do that with cartridge firearms anymore. Do they still run a proof load through each barrel, or is that practice lost to the days of blacksmiths pounding out barrels from wire wrapped around a rod?

I know in antiquity the proof was legally required and was typically a double charge with double projectile. What would be a smokeless proof charge? I know pressure curves get crazy so double pressure is rarely a double powder charge.

 

[hdwhit]

WestKentucky asked:
Do they still run a proof load through each barrel...

Proofing requirements vary by jurisdiction, but in countries governed by either SAAMI or CIP, every firearm must be proofed before it can be sold.

The pressure of the proof load for a particular cartridge is determined by whoever is responsible for maintaining the specifications and standards of the cartridge. In countries where SAAMI or CIP govern the proofing regime, a proof load will typically generate around 130% of the cartridge's maximum design pressure. There is some variability because of differences in where on the chamber the pressure is measured and how it is measured.

 

[hdwhit]

This is a link to a video produced by Izhmash, one of the factories that continues to make the AK line of rifles following the disillusion of the Soviet Union. Near the end, it shows rifles being proofed.

 

[Mizar]

It depends - in the US there are no Proof Houses for civilian firearms. Proof testing is voluntary and it's done by the manufacturer, usually according to SAAMI specs. But SAAMI does not proof firearms themselves, they only provide the needed data and imported firearms do not require reproofing. CIP is the same - voluntary organization that only sets the standards, but with the difference that at least in Europe every firearm must be proofed in an officially recognized Proof House (CIP membership is international, it's not Euro-specific). Proofing is obligatory for all the European countries, not only EU member states. Furthermore, CIP member states does not recognize proof tests from non-member countries and they require reproofing - for example, a Serbian, or Bulgarian firearm, while proofed in the country of origin and bearing the proper proof marks must be proofed again if it's imported to France, or Germany. Military guns on the other hand are, in general, always proofed no matter the country of origin (but with different standards). So, in a nutshell: European guns - every one of them is proofed, US guns - most of them are proofed...
This article should get you started on the subject: http://firearmshistory.blogspot.bg/2011/01/testing-firearms-proof-test.html

 

[Jim Watson]

Yup. Most first world countries have government proof houses. US makers proof test with liability lawyers looking over their shoulders.

The usual proof test is a 30-33% chamber pressure overload.
There is a How it's Made video of a Uberti revolver being assembled with the statement that it is tested at "three times the usual pressure." Another reason not to get your information off of teevee and youtube.

 

[mcb]

I don't believe proof testing is required in the US by law or even by SAAMI voluntary standards.

Proof testing, although proving the firearm is strong enough to withstand the over-pressure load, is ultimately shortening the firearm's life (the amount depends greatly on the particular design). Also if you are proof testing a firearm without post-proof inspection you have done nothing but abused the gun. If you proof a gun you need someway to inspect the parts after the test to ensure the proofing loads have not introduced potentially catastrophic damage to the parts. Some of that damage can only be detected by inspection methods like mag-partial inspection and similar methods that can detect microscopic crack initiations.

I think (hope..) we will see proofing go away. We have technology that can show there are no flaws in the material of critical parts without the need to over-stress them in a proof test. Mag participial inspection, X-ray, ultra-sonic, etc testing can tell you if a part is good or bad without abusing the part to prove it is good. This technology is getting more and more accessible and ultimately should be cheaper. Since you really should be inspecting post proofing anyway, skip the proofing all together and simply inspect the parts. I would much rather have a barrel and bolt that have been mag-partial inspected and never proofed than a barrel and bolt that have been proofed and then not inspected.

 

[Bbear]

15 or so years back I was lucky enough to take a tour of the Sako/Tikka plant in Finland. There, they showed us the 'proofing' room. Two folks were loading one rifle after the other into a protected area and firing 150% proof loads (2 of them) through each rifle. After firing, each was then checked for any problems before moving over and having two guys spend their days shooting each rifle for accuracy. Pretty interesting tour.

 

[Jim Watson]

A job like that would cure me of shooting as a sport.

NDT sounds modern and all, but from what Slamfire says, we STILL don't have a way to identify "burnt" low number 1903s besides hitting them and seeing if they break.

 

[klausman]

You Know, you have to wonder about a guy from Tennessee or Kentucky asking about barrel proof.