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Discussion Starter · #1 ·
By observation it appears that the powder in a shot shell is normally loaded to a compressed state, as in there is no space above the powder charge like in a normally load CF rifle cartridge. Would this be generally correct? Would you expect (in general) the same peak pressure if one were to use the components from a shot shell and load them into a muzzle loader of the same bore size? Larry
 

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By "components" i hope that you are not considering using smokeless powder as part of that mix. If so, it is not a good idea.
The two "systems" are quite different. A shotshell is a closed system...once ignition has commenced, the only way for the pressure to be relieved is to push the shot load up the barrel and out of the muzzle.
In a MLer, whether it is a flintlock or a caplock, there is - effectively - a vent at the rear of the barrel...the nipple or the flash hole. Pressure escapes, to a degree, through that vent upon firing.
Black powder does not, under normal circumstances, reach any where near the peak pressures generated by smokeless propellants.
Remember that many, if not most, popular smokeless shotgun powders are essentially plasticsized nitroglycerin/nitrocellulose. The pressures produced by their use in a firearm is wildly different than black powder.
 

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Discussion Starter · #3 ·
By components I was referring to all the parts/material inside a shotshell. If I were to eliminate the shot cup holder or the buffer material behind the slug, would the peak pressure remain the same as with it? This is for use in a special built gun, not an existing ML, so while I know you have good intentions to keep me from shooting my eye out, I am really only interested in knowing if the buffer material or the shot cup reduces the pressure in the shell when it is fired. Larry
 

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from how i understand it, the shot cup keeps the shot together while its in the barrel and thru whatever choke is in place.
the buffer, reduces the shock on the shot , helping to keep it uniform in the cup
the chamber pressure in a 12 gauge shotgun, regardless of shell is something like 12.5 to 15 K psi max.

i think the buffer does not reduce the chamber pressure .. i do think the chamber pressure would remain very close if not the same if you removed the buffer or shot cup.
 

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My thought is "OP" wants to know if shotshells have the powder compressed under the wad compared to a rifle cartridge where the powder is loose. If there is will be a deference in pressure between the two. What if you loaded a 12 gauge slug with out the built up wad filler or compression of the powder.
 

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If I were to eliminate the shot cup holder or the buffer material behind the slug,
Eliminate the shotcup. Use just the base of the wad. Put the Slug atop that. That would work. There is a "however"....the however is that BP is not kind to plastic components. They melt.
Pete
 

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Discussion Starter · #7 ·
Vash the Stampede Yes, exactly right, no BP, use the smokeless in the original. All the stuff in the shotshell minus the shot cup or filler ahead of the powder. A wad on top to hold the shot or slug in the barrel. Larry
 

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i don't believe there would be any more pressure
from a compressed load of a particular burning
rate of powder than one not compressed unless
you were to inadvertently grind some of the granules
to a finer state by compressing the load. i'd think
that would apply to any type of ammo as well as shotshells.
i don't think modern powder knows if it burns contained
in a shell, or inside of a barrel without being contained
in a shell. i think what makes a difference is the
force necessary to get the payload scooting down the barrel.
 

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Discussion Starter · #10 ·
Thanks for the info, kind of what I thought. I built version 1 to 5X the calculated value, now version 2 built to a safety factor of 1.5X. It looks much better in the lighter version. Larry
 

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Scibaer said:
from how i understand it,
the shot cup keeps the shot together while its in the barrel and thru whatever choke is in place.

the buffer, reduces the shock on the shot , helping to keep it uniform in the cup.

the chamber pressure in a 12 gauge shotgun, regardless of shell is something like 12.5 to 15 K psi max.

i think the buffer does not reduce the chamber pressure.
i do think the chamber pressure would remain very close if not the same
if you removed the buffer or shot cup.
Scibaer is spot-on IMO. :)

Will you share data / pics on your project Trotter? :D
 

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Discussion Starter · #12 ·
You seem to likely be correct, I did the calculation on the thickness needed for the barrel and loaded all the components from a 410 slug round in a barrel that is .400 bore. Pressed in a small cork on top of the slug to keep it from falling out and shot it. Big bang and no problems with the gun, the primer looked good so I think it is good to go. Shot it 8 more times with one loaded with components from a shot shell, still no issues. Larry

 

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trotterlg said:
You seem to likely be correct, I did the calculation on the thickness needed for the barrel and loaded all the components from a 410 slug round in a barrel that is .400 bore. Pressed in a small cork on top of the slug to keep it from falling out and shot it. Big bang and no problems with the gun, the primer looked good so I think it is good to go. Shot it 8 more times with one loaded with components from a shot shell, still no issues. Larry


Neat. Where is the hammer? How do you cock the thing?
Pete
 
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