Why did this rifle blow up?

Yikes. That's almost always really really unwise.

As expected. I wonder why they'd waste a rifle to prove that that would happen? Was this mythbusters or something?

There were bolt action black powder rifles built in the 1800s, which wasn't your question but it's interesting. 11mm Mauser, for example. More a "thrust" than a "slap" when you shoot it.

Burn rate & pressure curves. You can get the same velocity with black powder, but it burns "differently" (there, weasl-y enough?)

Yes, yes, and yes, in that order.

About as clear as my answer, sorry. rec.guns might be another place to talk about this, chances are good someone saw the same show you did and has more details.

Dave Hinz

But then, I don't think so good. Anyway, since the rifle blew

The show might have shown one of the new inline muzzle loaders that have the powder and bullet loaded from the muzzle, then the bolt is opened and the primer inserted on the back of the chamber. That would account for a bolt flying out the rear. But there are also standard cartridges that can be loaded with black powder like the .45-70 or .44-40 so a "black powder rifle" is not necessarily a muzzle loader.

Smokeless is more powerful than black powder and burns faster so it creates more of a pressure spike. The modern powder to be used in muzzle loaders in place of black powder is called Pyrodex. To give you an idea of how much more powerful, in cartridges like the .45-70 you would use 70 grains of black powder but only 40-50 grains of smokeless. Obviously a grain for grain substitution is going to be a big problem.

It's not a matter of weaker materials, just design specs. For example, a shotgun is designed around a cartridge that produces a maximum of maybe

15,000 PSI of pressure. A cartridge like the .308 is designed around a pressure limit of 65,000. Guess what happens if you subject a shotgun to 65,000 PSI? I don't know what a typical design pressure would be in a muzzle loader but I suspect it's closer to shotgun than .308. Manufacturers design the firearm around the SAAMI specifications for pressure and the ammo produced to those specs (or the loading instructions in the case of muzzle loaders). As long as everyone follows the rules when making their own ammo or loading their muzzle loader we all get home safely!

Steve.

Depends what kinda of smokless powder they tested it with, and how much. If they put 50 grains of pistol/shotgun powder double base powder like WW231 or Reddot, it would blow up any gun, modern or old.

If they used a progressive burning rifle powder 3031/4895/7831, the barrel might not be able to handle the peak pressure, espeically with large bore//thin barrel muzzleloader.

So, it depends on how big the load, and what kinda powder.

I would never replace black powder with smokeless; it's a whole different animal. Very different ingredients, burning rates, and hence power produced. You're asking for a lot of hurt! Lane

I missed the staff meeting but the minutes show Eric R Snow wrote back on Wed, 02 Feb 2005 10:55:06 -0800 in rec.crafts.metalworking :

Nope. There are still some cartridges made with black powder.

Basically: yes. Smokeless powders, especially modern powders, have more "bang" per unit volume than black powder. So if you filled a black powder cartridge with the same volume of smokeless powder, you're putting a serious charge in there.

Yes.

Black powder rifles can get away with lesser strength than a smokeless powder rifle, but that is a lesser issue.

Most of it has to do with modern powders producing higher pressures than BP. Kind of like burning Aviation Gas in something designed to use Kerosene.

tschus pyotr

Not at all. See, e.g., for blackpowder cartridge rifles.

-jc-

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