18 tons per square inch.


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elvishoot3r
March 7, 2013, 02:14 AM
My brother wants to buy a hunting rifle. I want to get more info on it b-4 he does it. all we know is 30-06 it says alpine customs, firearms of england ,los alamitos california and GNP and a crest and 18 tons per []" on the barrel please help.

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tahunua001
March 7, 2013, 02:23 AM
a google search will reveal a number of people asking the exact same question you are. none of them seem to get a stone solid answer but the following themes seem to fit.

1. they are custom rifles built off a 1898 mauser action.
2. they are all 30-06 caliber
3. they all have england and los alamitos stamped on them somewhere.

I can't tell you who built it or whether it was done in england or california but I can tell you that if all you really want is a hunting rifle then I wouldn't dump the money into a custom built rifle, a cheap remington, savage, winchester or other mainstream brand easily available at walmart would probably suit you fine.

joneb
March 7, 2013, 04:21 AM
18 tons per square inch implies 36K psi:confused:, 30-06 runs 50-56K psi

Shadow 7D
March 7, 2013, 04:39 AM
Golden State Arms, couple of names (forget the overall company)
2 styles

ONE Enfeild, great guns, has difficultly taking NOT 303/conversions
TWO Enfeild 1914 (also known as England's Mauser cause, well it's a Mauser)
easy to work on, much like the M1917
There was a huge industry in the late 40's early 50's in surplus arms
without knowing the action, not much to say.

natman
March 7, 2013, 04:42 AM
18 tons per square inch implies 36K psi:confused:, 30-06 runs 50-56K psi

This sort of confusion is what happens when you apply common sense and logic to British measurements. :D

I found this quote several times while searching for "British proof":

"Per the 1954 Rules of Proof, here are the equivalent service pressure values:
3 tons--8,938 psi "

Don't ask me how that works.

Anyway, 6 times 8,938 psi = 53,628 psi = 18 "tons" per square inch, about right for a 30-06.

JohnBT
March 7, 2013, 09:47 AM
The problem appears to be that way back when they used a Lead Crusher Radial system to proof firearms. When they began changing over to a newer system they had to settle on a number to use in the conversion formula because they couldn't figure how the old system complared to the new one. I'll quote a guy who appears to know a lot about it.

http://kwk.us/pressures.html

"No accurate conversion between crusher and true pressure exists, but approximations can be made"

Jim Watson
March 8, 2013, 10:14 PM
Pre-metrication British chamber pressures are:
1. Based on the long ton of 2240 lbs,
2, Measured with an axial crusher gauge with element in a modified bolt head, not a radial gauge with hole in barrel.

These combine for lower numerical readings than US radial crusher gun CUP and lots lower than piezo psi.
It does not mean that the rifle has not been thoroughly tested and it is not unsafe with fresh ammo.
Your gun is fine.

Jim K
March 8, 2013, 10:18 PM
FWIW, 2979 pounds is 1 1/3 British long tons (2240 lbs). I have no idea what that means but thought it might be worth mentioning.

Also, the SAAMI figures usually given are the MAP, or Maximum Average Pressure, or the maximum pressure a factory cartridge should have. The British proof test marking is the average working pressure, which would be considerably lower than the MAP.

Jim

elvishoot3r
March 10, 2013, 04:15 PM
Thanks to all that replied, I now have a better understanding of what the rifle is.

Jim Watson
March 10, 2013, 06:49 PM
Gough Thomas correlated British and Yank pressure ratings and concluded that a long ton of load on a axial crusher was equivalent to about 2800 lbs dead load on a US type radial crusher gauge.

backbencher
March 12, 2013, 07:25 PM
Think British proof loads are quite a bit higher than normal.

http://kwk.us/pressures.html claims British proof loads ran 30-45% above the stamped pressure.

JohnBT
March 13, 2013, 10:35 AM
I like the sentence that followed that statement, the one about oiling proof cartridges.

"Under the British base crusher standards described below, proof loads ran 30 to 45% above normal. To maximize breech thrust, proof cartridges were oiled before firing."

waidmann
March 13, 2013, 08:14 PM
I think GNP is a lightly struck BNP or Birmingham Nitro Proof. Alpine was one of several smaller houses in that market and manufacturing center that were dominated by Parker-Hale and Birmingham Small Arms (BSA). Parker-Hale and all others (BSA excepted) used Mauser 98 style actions. There is plenty of proof info on ther net.

The other info described would be the importer's marks.

I am sure it is a fine rifle.

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