Eric R Snow wrote:

I caught the last half of a shooting show where the theme was black
powder vs modern high power smokeless powder. To demonstrate the
difference and graphically show the difference a modern black powder
rifle was loaded with smokeless powder and fired. I missed the part
where they were loading it so I don't know how much powder was used or
the size of the bullet. I came in where the rifle was placed in a
braced position with a string tied to the trigger. The fellow went
around the corner of the shooting shack and pulled the trigger. The
rifle blew apart. It looked like a bolt shot backwards out of the
rifle.But since it was a black powder rifle there may not have been a
bolt. In fact, I thought all new black powder rifles were muzzle
loaders. But then, I don't think so good. Anyway, since the rifle blew
up was it because modern powder is so much more powerful than black
powder? Or is it because more black powder is used per round and when
using the same amount of more powerful smokeless powder it would blow
any modern rifle? Or is it a combination of weaker materials being
used in modern black powder rifles compared to rifles that shoot
smokeless powder and the higher power powder being used in the same
amount as the lower power powder?
Hope the preceeding was clear.
Thanks,
Eric

As the others have said, smokeless powder of any sort has completely
different characteristics than black powder has, especially when lit off
in a confined space. The pressures from black powder are quite low, on
the order of 20k psi (IIRC) while a typical pressure for a modern
smokeless cartridge will be in the 50k or less psi range to be
considered safe.

In many cases the slow rate of burn of black powder (if coarse enough
grain size was used) would cause excess amounts to be ejected with the
bullet and thus be self limiting, to a point. It is quite possible to
blow up any modern firearm by loading too much, too fast burning powder
as well.

As to the bolt blowing out the back. Traditional muzzle loading weapons
had the barrels made as a tube, with a plug, often incorporating the
tang and flash hole, screw threaded into the breech end. It is possible
this was what you saw come out of the back.

Cheers
Trevor Jones