+ Reply to Thread
Results 1 to 9 of 9

Thread: Proof firing

Click here to increase the font size Click here to reduce the font size
  1. #1
    Member scharfschutzen63's Avatar
    Join Date
    Jul 2008
    Last On
    Today @ 08:25 AM
    Posts
    24
    Local Date
    12-10-2018
    Local Time
    12:10 PM

    Proof firing

    I just happened to check. I have a no4 and a no5 enfield. Both are proofed 18.5 tons per square inch.
    Enfield 7.62 barrels are proofed at 19 tons.
    This is only 1000 psi more I am thinking. This is not much in relation to the overall pressure, but could still be beyond the failure point for a part that passed the 18.5 ton proofing.
    19 tons per square inch is 38000 psi. In metric tons, just under 42000 psi
    SAAMI Spec for 308 Win is 52000 cup.
    I am thinking the units are different.
    Can anyone shed some light on all of this?
    Last edited by scharfschutzen63; 09-16-2018 at 01:14 PM.

  2. # ADS
    Friends and Sponsors
    Join Date
    October 2006
    Posts
    All Threads
    No Drill-Tap scope mounts for Mosin Nagant, Mauser K98K, Yugo M48, Swedish M96 and M38, Swiss K31, K11, 1911 and more! Bringing mil-surplus rifles to modern standard without damaging historical values! We specialise in military utensils and artefacts such as helmets, daggers, medals and badges, etc.  The on-line store is intended for personal browsing and searching of collecting objects. All items are provided historical value only and can be used for home collection or other purposes except of fascism, Nazism or other extremism manifestation or its propaganda. LIMITED TIME OFFER FROM THE AMERICAN GUNSMITHING INSTITUTE: Get Immediate Online Access To AGI's NEW Armorer's Course for Glock Pistols, Covering Every Generation of Glocks, Including the Latest Model 42/43 and Double Stack Pistols for ONLY $7.00! Brian Dick ... BDL Ltd. - Specializing in British and Commonwealth weapons Chuck in Denver ... Buy-Sell-Trade .. Guns, Cars Motorcycles We pride ourselves on being the new lowest price listing service, and the simplest to use. If you need to buy or sell collectible firearms or any firearm in your legal possession, then this is the place for you. If you’re a big collector clearing house, or other seller that could benefit from a Premium seller account, then we can also support you here at Armory.Auctions LLC. Your source for the finest in High Power Competition Gear. Here at T-bones Shipwrighting we specialise in vintage service rifle: re-barrelling, bedding, repairs, modifications and accurizing. We also provide importation services for firearms, parts and weapons, for both private or commercial businesses.
     

  3. #2
    Advisory Panel
    Peter Laidler's Avatar
    Join Date
    Jul 2008
    Last On
    Yesterday @ 08:50 AM
    Location
    Abingdon, Oxfordshire. The home of MG Cars
    Posts
    15,771
    Local Date
    12-10-2018
    Local Time
    07:10 PM
    My wife is a mathematician and pretty good at sums and especially good at counting and claiming expenses from work. But to be totally honest, she is out of her depth when it comes to the mathematical mumbo-jumbo that surrounds the mystical world of proofing. She says that it is all based on white mans magic and the phases of the moon in relation to the tidal equinox.

  4. The Following 7 Members Say Thank You to Peter Laidler For This Useful Post:


  5. Avoid Ads - Become a Contributing Member - Click HERE
  6. #3
    Really Senior Member Bruce_in_Oz's Avatar
    Join Date
    Jun 2008
    Last On
    Today @ 07:17 AM
    Location
    Brisbane
    Posts
    1,698
    Local Date
    12-10-2018
    Local Time
    12:10 PM
    It seems there are different "units", depending on the measurement method.

    PSI, Megapascals, etc are one thing, but the method of estimating the pressure within a cartridge after ignition is interesting in itself.

    If you see "C.U.P" in the description, that stands for Copper Units (of) Pressure. This involves a small cylinder of copper to be , literally, crushed by the pressure. It is used in proof and metrology labs to evaluate ammunition and to develop "proof' cartridges. The set-up is surprisingly basic. A HEAVY test barrel in a Mann rig has a small hole bored diametrically into the chamber, usually at about the half-way point.

    This hole is for the copper plug, which is retained by a collar or similar. When the cartridge id fired, the pressure punches a hole in the brass case and then acts on the captive copper "plug" the result of this compression is measured and compared to data from plugs compressed hydraulically in carefully calibrated presses. It is a good "indicator" method.

    A more modern method involves fitting a series of piezoelectric sensors. (pretty much "lab-grade" strain gauges), to the barrel reinforce and sometimes forward along the barrel. These give "instantaneous" readings as the barrel "stretches" radially at peak pressure. This is a complex process, but a rather "neat" system because it is non-destructive, unless the firearm under test is seriously defective. The techies crunch the numbers to arrive at a pressure figure.

    Firing is usually done in a hardened room and the arms under test are often housed in heavy steel hoods, to catch the bits if it all goes wrong. The operators are usually in an adjacent room, firing by remote.

    Final part of proofing involves the careful inspection of all "pressure-bearing" components to find any distortion or incipient cracks. REALLY good proof establishments also clean the tested arms to prevent nasty surprises when the owner opens the box, a few weeks or months down the road.

    I reckon if you go to the SAAMI and CIP sites you will find more than you ever wanted to know about the whole business.
    Last edited by Bruce_in_Oz; 09-16-2018 at 05:50 PM. Reason: Typos

  7. The Following 6 Members Say Thank You to Bruce_in_Oz For This Useful Post:


  8. #4
    Really Senior Member nijalninja's Avatar
    Join Date
    Nov 2017
    Last On
    Yesterday @ 11:10 PM
    Location
    Australia
    Age
    20
    Posts
    333
    Local Date
    12-11-2018
    Local Time
    03:10 AM
    An old Lyman book I have details the differences in the two main processes for determining pressures, but I'm afraid I'll have to wait to tomorrow to read it and post up the wisdom. That is if its not already answered by then. From what I remember of it Bruce is on the money completely.

  9. #5
    Contributing Member CINDERS's Avatar
    Join Date
    Nov 2009
    Last On
    Today @ 10:22 AM
    Location
    Southern Corner Western Australia
    Posts
    5,466
    Local Date
    12-11-2018
    Local Time
    01:10 AM
    Real Name
    CINDERS
    Yes the good old C.U.P measurements they used to use.........................just another one for the mix that Peter Laidlericon points out on the subject.

  10. #6
    Advisory Panel Parashooter's Avatar
    Join Date
    Dec 2008
    Last On
    Today @ 12:00 PM
    Location
    Connecticut
    Age
    73
    Posts
    578
    Local Date
    12-10-2018
    Local Time
    12:10 PM
    Do keep in mind that the traditional Britishicon system of pressure measurement employed an axial crusher, located behind a floating breech face and driven not by a radial piston but by the lubricated cartridge itself. The results are quite different from either the radial crusher system or modern transducer systems.

    Remember also that the pressures marked on British-proofed arms are in long tons (2240 lb.).

  11. #7
    Really Senior Member Paul S.'s Avatar
    Join Date
    Mar 2009
    Last On
    Today @ 02:08 AM
    Location
    Back and forth between Sydney and Southern California
    Posts
    1,417
    Local Date
    12-10-2018
    Local Time
    12:10 PM
    Quote Originally Posted by Peter Laidlericon View Post
    She says that it is all based on white mans magic and the phases of the moon in relation to the tidal equinox.
    Peter, that's the funniest thing I've read in a week at least. Thanks for the laugh Mate!

  12. #8
    Advisory Panel
    Peter Laidler's Avatar
    Join Date
    Jul 2008
    Last On
    Yesterday @ 08:50 AM
    Location
    Abingdon, Oxfordshire. The home of MG Cars
    Posts
    15,771
    Local Date
    12-10-2018
    Local Time
    07:10 PM
    That reminds me Bruce......... We used to have a similar copper crushing method for testing the 'force of blow of the striker' for the old 2" mortar and some other equally obscure bit of kit........ I think it was the 1.5" signal pistol. You assembled this gadget with these copper cone shaped whatsits that had to fit whatever side up into the top half of the thinggy. But, alas, the EMER and every other booklet on the subject gave different points of view, depending if YOU were holding the contraption or whether the class teacher was holding the thing to show you. Then, together with a thinggy and then another whatsit you assembled this 'Gauge, testing something or other' and screwed it to the threaded mortar body. You wonder who invented it. I presumed that it was the same man who dreamed up time and motion on the battlefield. Anyway....... We all practiced hard with this gadget and took it all seriously - as you do. It took ages to get a result because each mortar had to be done three times and then a mean average had to be worked out and........... and........

    That was fine, until we took all of this newly learned knowledge to our first units. Mine was a front line Infantry demonstration battalion at the School of Infantry where we were knee deep in 2" mortars. That's when I realised that our special gadget for testing 2" mortar was rusting away, unloved and unused in the back of an old cupboard. That was when Johnny Sparrow taught me the way things were in real lofe, at the sharp end. He pointed out to a red line painted line on the wall, about 6 feet off the ground (and to one side of the florescent strip light I hasted to add.....). He then told me that to test OUR mortars - and the way that they were tested everywhere else in the known universe, - was by putting an old copper penny piece into the firing ring and pulling the landyard/firing lever. The spinning coin spun upwards and if it passed the red line, all was well. If not, you did it again until it DID spin past the red line.

    So simple............
    There was a little humourous sequel to this if anyone wants a laugh......

  13. The Following 5 Members Say Thank You to Peter Laidler For This Useful Post:


  14. #9
    Advisory Panel Surpmil's Avatar
    Join Date
    Feb 2008
    Last On
    12-02-2018 @ 04:44 AM
    Location
    Gold Mountain
    Posts
    2,621
    Local Date
    12-10-2018
    Local Time
    09:10 AM
    Don't know, but I saw a 1944 manual on the proofing of SA ammo on a library shelf recently and am going to photograph the whole thing.



    Badger can maybe find a home for it here somewhere?
    "Deer-stalking would be a very fine sport if only the deer had guns." W. S. Gilbert.

+ Reply to Thread

Similar Threads

  1. Proof mark? or what?
    By read6737 in forum Milsurps General Discussion Forum
    Replies: 7
    Last Post: 06-06-2018, 11:32 PM
  2. Enfield firing pin, firing pin spring compatibility SMLE vs No. 4 & other questions
    By Steve762 in forum The Lee Enfield Knowledge Library Collectors Forum
    Replies: 2
    Last Post: 01-02-2015, 07:55 PM
  3. What is this Proof?
    By Mikesm44 in forum The Lee Enfield Knowledge Library Collectors Forum
    Replies: 21
    Last Post: 11-23-2013, 03:36 PM
  4. Can someone ID this proof?
    By Garandrew in forum The Lee Enfield Knowledge Library Collectors Forum
    Replies: 4
    Last Post: 05-24-2011, 06:45 PM
  5. Proof Firing
    By Bill Ricca in forum M1 Garand/M14/M1A Rifles
    Replies: 23
    Last Post: 03-13-2011, 08:28 PM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts