375 Ruger vs 378 weatherby is it worth the extra $$$
- Thread starter Weatherby2
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One source purports the 9 lugs on the Mark V bolt to be interrupted sections of a screw thread. Compared to a dual lug design the intent is probably to provide more area for shear forces to act across thereby reducing shear stresses to make the action more rigid in the axial direction.
378 WBY ammo isn't listed in ANSI/SAAMI Z299.4. 416 WBY ammo is listed and shouldn't produce on average more than 53,500 CUP.
The Mark V rifle has been advertised as having the strongest action available so maybe WBY factory ammo is held to a lower maximum pressure in deference to WBY cartridge rifles built on other types of actions.
378 WBY ammo isn't listed in ANSI/SAAMI Z299.4. 416 WBY ammo is listed and shouldn't produce on average more than 53,500 CUP.
The Mark V rifle has been advertised as having the strongest action available so maybe WBY factory ammo is held to a lower maximum pressure in deference to WBY cartridge rifles built on other types of actions.
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nowarningshot
CGN Ultra frequent flyer
Thats putting it much more diplomatically than some would. Can certainly agree with you BUM, no offense Slamfire.
While I stick pretty close to books myself, I would feel completely safe on the range beside Douglas. Don't know if he could stand me being there....all the endless interruptions.
My 375 is a Rum. Have had a H&H before, twice, neither was unpleasant. The Rum, needed a brake....or I would have been broke. The worst recoiling firearm I ever shot was a Savage 110 7mag. No one ever shooting it could ever hit a piece of 4x8 plywood on the third shot.
Most issues with recoil are stock related. The Mark V is one of the best actions for true magnums, the stock is one of the worst. Their seems to be a conception that people who shoot large magnums are 6'5" former pro wrestlers. I am average height, but stocky, my length of pull is youth. I shoot the rums, and 416 Rigby. Have a 340, yet un shot.
All of the super magnums go well beyond the point were huge extra amounts of powder create very little gain in performance...yet increases in recoil, and muzzle blast...with here today gone tomorrow bore erosion.
If one was shooting 1000 yards, this would matter. However, I believe this is not the intention of the OP. If long range hunting is the aim, a 300wm or Rum. For dangerous game a lesser standard/old school African caliber such as the H&H, Rigby, or even nitro. Two other points. Any bore over 30 is pricey...if you don't reload, you should. If your not going to reload, check out the price of 378 wea; bet it's north of $160/box.
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Consider temperature effects. Ammo that is safe at cooler temperatures could develop excessively high pressures on a hot day. Speer warns that with loads using double base powders, pressures may increase dangerously under extreme cold. Is action and barrel strength compromised by extreme cold?
Seems ammo that is held to ANSI Z299.4 pressure limits is more likely to be safe to fire at temperature extremes.
Seems ammo that is held to ANSI Z299.4 pressure limits is more likely to be safe to fire at temperature extremes.
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As claimed by the designer -
"Roy found that the Mauser action
handled up to 70,000cup (copper
units of pressure), but he wanted an
action much stronger, something that
could handle 200,000cup. As such, he
designed the Mark V..."
https://www.nioa.com.au/uploads/prontoAPI/attachments/Weatherby_Mark-V_Review_-_Aust._Hunter_.pdf
"Roy found that the Mauser action
handled up to 70,000cup (copper
units of pressure), but he wanted an
action much stronger, something that
could handle 200,000cup. As such, he
designed the Mark V..."
https://www.nioa.com.au/uploads/prontoAPI/attachments/Weatherby_Mark-V_Review_-_Aust._Hunter_.pdf
h t t p s ://www.outdoorlife.com/answers/guns/weatherby-mark-v-action-proof-test
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 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. Breech 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).[3]
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Same verbage in that Aussie article link I posted. Now that's an axially rigid action apparently that seems to have been tested well past yield. As for its strength circumferentially...
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^^
Nice views of the Mark V action.
"...Testing the Mark V action was done
in a .300WM and a charge of 82
grains of 4350 DuPont powder pushing
a 180-grain bullet gave an average
breech pressure of 65,000psi.
The load was increased by two
more grains and it blew a primer in
a Mauser action, making the case
difficult to extract. The Mark V did
not show pressure until the load was
increased to 86 grains, but no extraction
difficulties were experienced
until the load reached 88 grains and
pressure was beyond 100,000psi."
https://www.nioa.com.au/uploads/prontoAPI/attachments/Weatherby_Mark-V_Review_-_Aust._Hunter_.pdf
Apparently, based on this anecdotal account, 6 grains more powder increased breech pressure from 65,000 psi to >100,000 psi.
The Mark V action bolt lug design seems to be quite robust to withstand bolt thrust axial loading since head space increased by only 0.001" after testing.
http://riflebarrels.com/a-look-at-bolt-lug-strength/
What's the effect on the chamber and barrel?
For any given chamber pressure, barrel hoop stress is larger in magnitude than axial stress so hoop stress is the design-limiting stress value. A review of chamber and barrel stress levels, for illustrative purposes only (not for design), based on a given chamber pressure for my Ruger No.1 7.62x39 rifle shows that chamber and barrel hoop stress is about 1.7 times chamber pressure. Chamber and barrel wall thicknesses are probably not much different proportionally for a Mark V rifle, or most any other rifle, so stress levels could likely be multiplied by about the same magnitude.
https://www.canadiangunnutz.com/forum/showthread.php/1619777-High-performance-7-62x39
A chrome-moly barrel is made of AISI 4140 steel and, depending on hardness, could have a yield strength of around 111,000 psi.
http://stainless.steelandtube.co.nz/wp-content/uploads/2014/06/HighTensileSteel4140.pdf
Then at a chamber pressure of 65,000 psi, chamber and barrel stress levels are about 110,000 psi - or just below yield strength. Sounds reasonable since many but not all typical sporting rifles have maximum operating pressures of around 65,000 psi, and ammo that complies with ANSI Z299.4 is held to about that pressure level.
If chamber pressure is increased to 100,000 psi then chamber and barrel stress levels could be well over yield strength, and stress cracks could develop at the bore surface where hoop stress level is highest. Cracks have a nasty habit of growing until catastrophic failure occurs.
Nice views of the Mark V action.
"...Testing the Mark V action was done
in a .300WM and a charge of 82
grains of 4350 DuPont powder pushing
a 180-grain bullet gave an average
breech pressure of 65,000psi.
The load was increased by two
more grains and it blew a primer in
a Mauser action, making the case
difficult to extract. The Mark V did
not show pressure until the load was
increased to 86 grains, but no extraction
difficulties were experienced
until the load reached 88 grains and
pressure was beyond 100,000psi."
https://www.nioa.com.au/uploads/prontoAPI/attachments/Weatherby_Mark-V_Review_-_Aust._Hunter_.pdf
Apparently, based on this anecdotal account, 6 grains more powder increased breech pressure from 65,000 psi to >100,000 psi.
The Mark V action bolt lug design seems to be quite robust to withstand bolt thrust axial loading since head space increased by only 0.001" after testing.
http://riflebarrels.com/a-look-at-bolt-lug-strength/
What's the effect on the chamber and barrel?
For any given chamber pressure, barrel hoop stress is larger in magnitude than axial stress so hoop stress is the design-limiting stress value. A review of chamber and barrel stress levels, for illustrative purposes only (not for design), based on a given chamber pressure for my Ruger No.1 7.62x39 rifle shows that chamber and barrel hoop stress is about 1.7 times chamber pressure. Chamber and barrel wall thicknesses are probably not much different proportionally for a Mark V rifle, or most any other rifle, so stress levels could likely be multiplied by about the same magnitude.
https://www.canadiangunnutz.com/forum/showthread.php/1619777-High-performance-7-62x39
A chrome-moly barrel is made of AISI 4140 steel and, depending on hardness, could have a yield strength of around 111,000 psi.
http://stainless.steelandtube.co.nz/wp-content/uploads/2014/06/HighTensileSteel4140.pdf
Then at a chamber pressure of 65,000 psi, chamber and barrel stress levels are about 110,000 psi - or just below yield strength. Sounds reasonable since many but not all typical sporting rifles have maximum operating pressures of around 65,000 psi, and ammo that complies with ANSI Z299.4 is held to about that pressure level.
If chamber pressure is increased to 100,000 psi then chamber and barrel stress levels could be well over yield strength, and stress cracks could develop at the bore surface where hoop stress level is highest. Cracks have a nasty habit of growing until catastrophic failure occurs.
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According to this source, barrel hardness ranges from 25 to 32 on the Rockwell Hardness C scale -
http://firearmshistory.########.ca/2010/06/barrel-making-making-modern-steel.html
Then according to the Lilja Precision Barrels website, barrel yield strength ranges from about 110,000 psi to 140,000 psi.
100,000 psi loads generate around 170,000 psi chamber and barrel hoop stress - well in excess of yield strength to risk the creation of stress cracks.
http://firearmshistory.########.ca/2010/06/barrel-making-making-modern-steel.html
Then according to the Lilja Precision Barrels website, barrel yield strength ranges from about 110,000 psi to 140,000 psi.
100,000 psi loads generate around 170,000 psi chamber and barrel hoop stress - well in excess of yield strength to risk the creation of stress cracks.
