[QUOTE=Mike Stahle;23875]
Quote:
Originally Posted by Robert Rambler
These were sort of an anniversary edition "Red Sweater" box, similar to what Winchester did with the Super X box. Original box is on top. Those are modern shells, might want to use caution in a Damascus gun!
So what makes the pressure high?
Is it the drams of powder "and or" the brand of smokeless powder?
This pressure thing is very confusing to me to say the least.
They were using smokeless powder back in the day before my Damascus
barreled gun ever left the Parker factory.
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It is a complex interaction of amount of powder, burn rate of the powder, amount of payload, and velocity (and a few other things, too). But for simplicity's sake, take a one ounce load that gives 1200 fps velocity. You can achieve that with a fast burning powder that gives the payload a swift kick in the rear, and a resulting high pressure peak. OR, you can achieve the same velocity with a slower powder that gives the payload a gentler shove that lasts much longer down the barrel, but results in a lower overall pressure. Once the shot clears the muzzle there's no difference - you've got one ounce moving at 1200 fps. The difference is in the rate of acceleration down the barrel.
Now, with any given load, anything you "increase" (payload, velocity, or powder charge) will also increase pressure.
Finally, you must remember that most modern shells (unless they are specialty shells made for vintage guns) are designed so they will work well in the ubiquitous gas autoloader that the Average Joe shoots. According to a Federal rep I talked to once, they feel they need around 8500 psi or more for the shells to operate smoothly in a wide variety of autoloaders (including the ones owned by the guys who don't clean them much). If their shells won't cylcle the average automatic, they will get a bad reputation among their largest customer base. Plus, fast burning powders with high pressures generally require less of a charge than slower burning ones to achieve the same velocity, therefore they are more economical for the cartridge manufacturer (less powder per shell). In any case, I would bet that even what we call "light loads" in modern shells are still generating 8500 psi or more. (I'm not including the so-called Ultra-Light loads that the manufacturers don't recommend for autoloaders - they could very well be lower than that).