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Thread: PROOF TESTING

  1. #11
    Happy Camper hcpookie's Avatar
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    I think steady pressure vs. impulse pressure would not be a concern unless the temper we off, no?

  2. #12
    No Hope For Me 1biggun's Avatar
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    So am I reading that that is 6 tons pressure?

    If that's the reading, then could we not calculate the yield strength per square inch of for example a 4140 steel based on the published specifications on all of the metallurgy websites?

    From that, we can determine how much load the locking lugs endure:

    We need a press that has a gauge readout. My cheap-o doesn't but I know there are presses out there that have an indicator so you know exactly how much you're pressing down.

    Using that we could test the bolt thrust with a trunion and a ram made from hard steel. Set the trunion on end and just press down with the ram until we reach 6 tons. If she holds, then let's repeat the process with whatever pressure calculation the published proof rounds generate.

    PRESTO we have a legitimate answer to whether or not the trunion will work with 308 max pressures. The best part is that we would not need to fire a proof round in the gun to do so - we would be much safer with the trunion on a press.

    Thoughts?
    Ive considerd a press before and i think i posted about trying it that way.

    i have a sagia 223 trunion (I think its 22mm) its about as light as I have seen and a rusty rommy bolt it would likely be the weakest situaation one could test with factory parts and I could use a regular trunion for abolut $25 more. Im thinking of installing a 308 barrel on it and not even building the entire gun just the reciver and FGC no gas port ect just a bolt and carrier and return spring and runing a heavy proof load. for the sets to mean any thing I need to know tha load is going to produse at least a certain pressure. Id like to see at least 70,000 PSI and 80,000 would be better. this is based ona 308 case head on a 62,000 PSI SAMMI pressure (I think 62,000 is correct)

    I could likely do every thing for under $120 if that, less if nothing fails.

    we have been at this almost 5 years now and we still dont know what is sensable and what is not. I have a son getting close to shooting this stuff and as right as I think I am Im not willing to risk his safety on it. Im confident the 300 savage loads are in the range of under proof bolt thrusts but still. It would be worth a few hundred dollars to have some professional testing done IMOO.

    Ive been concrned about posting my builds and recominations on safe pressures here for some time in fear that some one will get hurt. i have a 308 conversion and so far so good. BUT???????????????????????????????????????//

  3. #13
    No Hope For Me 1biggun's Avatar
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    I wonder what this guy would have to say about the matter. Varmint Al's Engineering Page - Finite Element Analysis of Structures
    Ive read some of his stuff and im lost after about three lines. I wish i could do the math like guy like him. i posted on his 243 model 7 remington evaluations some were and how chamber finish affected bolt thrust.

    IfI had half a clue what all that meant I would not be sitting in my shop playing with AK,s id be working some were designing some thing. I cant even write a hot girla phone number down right let alone add up numbers correctly ERRRR

    Im sure he could figure it out. but still with out putting a known proof round or several and setting it off all the analises in the world dont ease my mind. remeamber bumble bee,s are not susposed to be able to fly according to scientists.

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