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Pressure signs on shotshells

Discussion in 'Uncategorized Threads' started by Hap MecTweaks, Jul 19, 2007.

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  1. Hap MecTweaks

    Hap MecTweaks Well-Known Member

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    Fred, more than likely the first thing noticed with a plastic hull is the mouth will stretch making it taller when sitting beside other hulls. Also, the crimp folds will "iron" out making the hull end smoother. (first sign) Plastic will flow forward just like brass will in a rifle case, primers will flatten out more too. Hap
     
  2. waverider

    waverider Well-Known Member

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    Hap may be right but the Maximum Pressure for the 12 ga 2 3/4" shell is 11,500 psi. This is very low compared to the 30,000 to 50,000 psi that is the maximum pressure for rifle cartridges. It is never recommended to work up a load like in metallic reloading. Follow the tested and published loads exactly when loading the fastest load published. You need not concern yourself with fractions of inches in the pattern of a shotgun.

    Jason
     
  3. halfmile

    halfmile Well-Known Member

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    Primer indications will be there, but some primers are harder than others. Any analysis of primer flattening has to be quantitative, ie same batch of primers, different degrees of smash.

    Case length in my opinion may not be a good indicator, since there is a lot of variation in once fired cases at times. I see STS hulls with a lot of variation. AA is more uniform.

    I have seen extractor marks in some shells fired in autos.

    In other words, pressure analysis in shotguns is more difficult and not nearly as precise as in metallic cartridges.

    HM
     
  4. Quack Shot

    Quack Shot Active Member

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    U. S. Marine Retired

    There ARE no RELIABLE pressure indicators for shotshells. The use of pressure testing equipment would be required. Velocity is not a reliable indicator as well as primer appearance. That is the reason it is recommended to use the data EXACTLY as shown using the exact components listed. One indicator might be the catastrophic failure of one's firearm after firing 20,000 loads developing excessive pressure. If you need to know for sure, there are companies that will test your loads for a fee and provide pressure and velocity data.
     
  5. goosecall

    goosecall TS Member

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    U. S. Marine Retired, there are signs of excessive pressure, but at what pressure does the sings show up is the question? If I want more velocity I go to slower powder, and If I want real speed I use Hogdon LongShot powder, but them shot size variables come in with speed for patterns. 10tenner
     
  6. Hap MecTweaks

    Hap MecTweaks Well-Known Member

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    Reloading rifle and shotshells for longer than I care to remember, I've learned that chambers for both, are not created equal. Some rifles have tight chambers that will show signs of excessive pressure when an exact same rifle is used with the same loading, it shows normal pressure signs. Same thing with our shotguns.

    Hopefully, whatever ammo you decide to load, the signs of excess pressure remain a mystery for you. Follow the loading guides recommendations and weigh the powder charges for safeties sake. You'll never know when metal fatigue sets in with any kind of gun metal till it's too late. Working that metal excessively with extreme pressures causes fatigue sooner. Hap
     
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