Wish I could remember the source but it was about trying to blow up one of the Japanese Arisaka WW2 rifles. It took MANY attempts and if I remember, it was near impossible with severe overloads, to blow the thing apart.
PO Ackley did quite a bit of that, but so did US Ordinance.
Weatherby had some extreme testing done on the Mark V when it was new.
Proof testing of the Mark V action[edit]
Weatherby had intended that the new action would be the safest and strongest bolt action available. The rifle was marketed as the "The World's Strongest Bolt Action". The Mark V action has been tested to be able to contain up to 200,000 CUP (Copper Units of Pressure).[5]
The testing of the rifle was conducted on a production rifle chambered for the .300 Weatherby Magnum. Before testing was to be conducted, very thorough measurements of the rifle were taken so as to provide a benchmark for the testing which was to be undertaken.[6]
The first test was conducted using a 180 gr (12 g) bullet propelled by 82 gr (5.3 g) of Du Pont #4350 powder. This load provided 65,000 psi (4,500 bar) of pressure. This load did not show any pressure or extraction issues with the new Mark V action but caused a slight sticking of the cartridge case in the Mauser style rifle design. Subsequent testing was performed using the same 180 gr (12 g) bullet and using a powder charge of Du Pont #4350 which increased by increments of 2 gr (0.13 g) for each test thereafter.[3]
The second testing which was conducted with the 84 gr (5.4 g) showed no signs of pressure nor issues with extraction even though the measured pressure was close to 75,000 psi (5,200 bar). Firing this load in the Mauser rifle led to a blown primer and extreme difficulty was experienced in extracting the spent case.[3]
Using 86 gr (5.6 g) of Du Pont #4350 the cartridge began to show signs of pressure in the Mark V action. However, the case did not stick and extraction was performed easily. Breach pressure was found to be between 85,000–95,000 psi (5,900–6,600 bar). Measurements of the spent case showed that the case had stretched at the belt a mere .0005 in (0.013 mm).[3]
The spent case from the 88 gr (5.7 g) test led to a slightly sticking case, which in turn led to a slight difficulty in opening of the bolt. Measurements from the case belt showed that the belt had expanded from .533 in (13.5 mm) to .535 in (13.6 mm). The pressure generated by this load was 100,000 psi (6,900 bar).
The fifth test was conducted used a load of 90 gr (5.8 g) of Du Pont 4350. Firing this load led to some difficulty in opening the bolt, and the case was extracted when opened. The belt of the case still measured .535 in (13.6 mm). A difference in the diameter between the bolt head and the diameter of the barrel of .002 in (0.051 mm) per side was noted. No bulging of the bolt, receiver or the barrel was noted. Headspace was measured to be the same as prior to the testing.[3]
Further testing was conducted with a 180 gr (12 g) bullet lodged into the throat of the barrel. A cartridge loaded with the standard charge of 78 gr (5.1 g) of Du Pont 4350 and a 180 gr (12 g) bullet was fired into the back of the first bullet. It was found that both bullets exited the barrel. The primer had been pierced and the exiting gas entered into the bolt and hit the firing pin sleeve, which was loosened slightly. The bolt was opened by hand but the cartridge stayed stuck in the chamber. When the case was tapped out, it was found to be in good condition except for its pierced primer. It was found that the barrel, just in front of the receiver ring, had expanded from 1.147 in (29.1 mm) to 1.1496 in (29.20 mm). The diameter of the bolt head had expanded from .7178 in (18.23 mm) to .7190 in (18.26 mm). The head space had increased from .2163 in (5.49 mm) to .2174 in (5.52 mm). All other dimensions had stayed constant. This test was conducted 15 times. A test was conducted with a 220 gr (14 g) bullet lodged into the bore of the rifle and a 180 gr (12 g) grain bullet was fired into the back of this bullet. The result of this test found that the cartridge case head had expanded to .545 in (13.8 mm). After these additional 15 tests it was found that the head space was set back only a mere .001 in (0.025 mm)
