Quote:
Originally Posted by Dean Romig
Ron, you're missing one basic fact... These guns were built to the specifications of paper shotshell casings manufactured (cut) to specific lengths. All of the ammunition manufacturers (and there were far, far fewer then than there are today) adhered to specific measurements for paper shotshells.
We can't compare apples to oranges as in shotshells manufactured in the latter half of the 19th century and early 20th century and those manufactured today.
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I don't believe I'm missing the point -- I made that very point in my last sentence about roll crimped cartridges. I totally understand the difference between modern manufactured plastic hulls and the older paper shells.
Regardless of the material used, the cartridge has one length when loaded (roll crimp or folded) and a longer length after it has been fired. Although I read about the 1/8" into the forcing cone theory in the article Scott Chapman provided a link to interesting it doesn't make sense to me. The paper hull obviously has a certain thickness and if it is not allowed to open fully (because it is 1/8" into the forcing cone) the wad and shot column would get squeezed down to a smaller diameter before entering the bore. How can that possibly be a good thing? To me the ideal would be for the cartridge to open fully in the chamber allowing the wad and shot to enter the bore without any constriction. Obviously the chamber length can't be so long that gas can escape around the wad. The other factor is the chamber diameter and hull thickness -- I would think the prefect situation would be to have the inside diameter of the hull (after being expanded by the gas pressure) be the same as the bore diameter -- that way the wad and shot column could make a smooth transition from the hull into the bore -- a difficult task since hulls don't all have the same wall thickness.
Check out this illustration, esp (c) showing the expanding gasses escaping past the squeezed down wad and shot column (caused by the hull opening into the forcing cone):