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Thread: Henry big boy 357 mag max pressure

  1. #1
    Boolit Mold
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    Henry big boy 357 mag max pressure

    I'm new to reloading and downloaded the Reloaders Reference program, I looked up the 357 mag load for bullet I am using. It said 8.4 grains of Longshot so I loaded 100 rounds. After doing some research I found that the max SAAMI pressure for a 357 mag is 35,000. The load data I used says it would be 43,200. I haven't shot any rounds off yet thinking this might be too much for the Henry Big Boy 357 mag. Should I go ahead and shoot them off or should I reload them to a lower pressure?

  2. #2
    Boolit Master


    fecmech's Avatar
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    Butch--I'm' guessing since you did not give the bullet wt that you are loading the 158 xtp? If that is the case the data you are referring to in the Hodgdon Guide is not PSI but 43,200 CUP (copper units of pressure) which is simply a different way of measuring pressure. Hodgdon is not going to publish an overpressure unsafe load. That said, it is a published max load which should be worked up to not started at.
    "The ultimate result of shielding men from the effects of folly is to fill the world with fools."
    Herbert Spencer (1891)

  3. #3
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    lathesmith's Avatar
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    Max loads are to be worked up to, and not used as starting loads. The sensible thing to do if you have any doubts is to start lower and work up to the max, watching for signs of pressure. That doesn't necessarily mean you need to disassemble what you already have loaded, but I wouldn't shoot them until you know they are safe.

    The only exception to this is if the powder is one of those that the maker lists loads for that are marked DNR--"do not reduce". These should be safe to fire as listed--so long as you are sure your measuring equipment is accurate.

    lathesmith

  4. #4
    Boolit Mold
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    Thanks for the info, the load data I was using didnt say if its a starting or max load. I went to Hodgdon's web site and found that a starting load should be 7.3.

  5. #5
    Boolit Man 44magLeo's Avatar
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    Being a new guy to loading, you might want to get a reloading manual.
    Most start out talking about why to reload, then moves into how to reload.
    Read it well, understand it.
    Reloading is an enjoyable hobby. If done properly, if not it can hurt you.
    On the pressure, the smaller numbers are generally CUP units, the larger numbers are PSI units.
    The pressure is about the same just two ways to measure it.
    Often this is covered in the reloading manuals.

  6. #6
    Boolit Master hickstick_10's Avatar
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    Quote Originally Posted by 44magLeo View Post
    Being a new guy to loading, you might want to get a reloading manual.
    Most start out talking about why to reload, then moves into how to reload.
    Read it well, understand it.
    Reloading is an enjoyable hobby. If done properly, if not it can hurt you.
    On the pressure, the smaller numbers are generally CUP units, the larger numbers are PSI units.
    The pressure is about the same just two ways to measure it.
    Often this is covered in the reloading manuals.
    Agreed
    This advice is VITAL

    Buy a reloading manual and read i first, you shouldn't be reloading cartridges if you dont have one.

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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check