ovenpaa wrote:Robert, thank you for reply, I have learnt something. It does however lead me onto another question. Obviously the test rounds are fired and the action and barrel inspected along with the fired cases and assuming there are no signs of damage everything is proof stamped, however how do they tell the pressure that it has been tested to, or do they not look for the pressure so much as signs of significant over pressure such as cratering, hard bolt lift and then *assume* based on the barrel and action manufacturers and previous experience that the new cartridge is safe to use?R.G.C wrote:Pertinent question, difficult reply.
I do not think the question should be addressed to aussies, as there is no proofing procedure, nor norms on the subject in their country.
There is two lists of calmibres:
-SAAMI (Society of Arms and Ammunition Makers Industry), USA Industry association who is what its name says and who establish recommendations, not rules.. I believe entering a caliber in the SAAMI list is not very much of a problem. Their measurements are Imperial
-CIP (Commission Internationale Permanente pour l’Epreuve des Armes a Feu et des Munitions) (Sorry, the official CIP language is french!!).
<Snip>
Ovenpaa,
Have a raad at:
http://en.wikipedia.org/wiki/Commission ... Portatives
Proof ammunition is tested separately in pressure test guns and designed such as the peak pressure (the 25% over the listed pressure for the calibre) is intended to happen at as near as possible to the chamber. In other words, they are quite fast burning powders for the calibre.
Of course, those rounds specification are established in advance, from firing in test barrels who can record the Piezo pressure. There is no guarantee that the same pressure is developed in the gun submitted to the proof (Although that with the tight chambers, long barrels and also tightbores of our match rifles, pressures developed on testing are probably higher than the 25% in prof evelopped in shrt standard sized proof barrels…)
As the protocole digest says (I have it in full somewhere here), no care is taken about the cycling or the condition of the fired cases. This is not the purpose of the proof.
Each time I went to proof house for a proof, I recovered the empty cases, as they gave precious indications as to the chamber dimensions, etc, etc. I do presume that the relatively fast burning powders does not show the same evident signs of pressure that slower burning powders could give?.
The ‘special proofing” using ammunition heated at 80° (I thnk I rememeber ths was the temerature) for 2 hours gives certainly at least 50% more instant pressure and, when using this method, signs of pressure on the cases are more evident… I only saw this process once, and dod not inspected the xases..
At the old St Etirnne proofhouse, there was a ‘museum of horros’ of firearms having not resisted to the test. I remember particularily a rifle whose barrel was split in 4 long strips just like the dowels of a beer barrel. The 4 segments were at a diameter of at least 200mm at the centre, and the barrel was kept together at receiver level …and by the barrel band at front, believe it or not… This happened some 14 years ago. I do not know what happened from the old collections when they moved in their new premises?.
R.G.C
#