I don't know about blowing the hand off, but you are likely to have a good size hole through it!
Yes, this kind of thin has occurred. Not often, but once is TOO OFTEN, particularly if its YOU! And the fact that it can happen is the reason for the rule.
When I began shooting BP in the 70s, it was considered OK to simply blow down the barrel to extinguish the burning embers and blow the smoke out the vent or nipple. This softened the residue with the moisture in your breath, and proved that the flash channel, or the vent hole was not blocked.
We later changed that practice, at our club, prohibiting the old practice all together, because we caught a man whose gun had misfired blowing down the barrel! The shot did not fire, but if it had let go, the muzzle would have been in his mouth and the results would be unthinkable.
Using a proper cleaning jag, and a dampened cleaning patch will acomplish all the same benefits, softening the residue, extinguishing embers, blowing( pushing ) smoke out of the nipple or vent. In addition, it actually removes the residue so that the area of the breech that holds the powder for the next shot is not enlarged with crud, making for lower pressures, and a ball soing to a different POI.
Finally, by changing the safety practice, we complied with the most important rule of gun safety : Treat Every firearm with the same care and respect afforded to a LOADED firearm. Never point the muzzle at anything you don't intend to destroy. By doing so, we set a better example to those people who know nothing about shooting MLers, but watch us shoot and reload.
NOw, having blown down my barrel for years before our change, I am not going to get into that old debate about whether blowing down the barrel of a Muzzle loader is " Safe". ( I still think it is, as long as the rest of your brains are in gear!)Claude has left up a post topic on Blowing down the barrel if you want to read all the arguments, for an against. I am NOT GOING TO TRY TO Persuade someone who has been blowing down the barrel of his gun for many years, that the practice is Dangerous, per se. ( Its only slightly more dangerous, when the operator is brain dead!)
With my gun club, I am the attorney for the club, and the officers and directors ask me if the club could be exposed to liability if someone blew down the barrel after a hangfire and injured or killed himself. I told them I knew several Plaintiff's lawyers who would not hesitate to sue the club if we knowingly allows an " unsafe practice " to go on during club shoots. And, our Insurance carrier would not be happy, either.
At the time, most insurance companies were stopping their coverage of gun clubs and ranges. The NRA got involved and arranged for Kirk Van Arsdale, in Iowa, to underwrite insurance for Charter clubs, and that was the only way we could be insured. ( We had been insured by a company out of Minnesota before they dropped out.)
The Board was faced with a serious issue. OUR landlord required, as a condition of our lease, that we maintain liability insurance, and that the landlord be named as a co-insured. Without the insurance, our lease was null and void. We would lose our range. The Insurance policy also was void if there was anyone drinking alcohol anywhere on the leased grounds while the firing line was OPEN! So, the board took the drastic step of imposing some strict, " NO-Drinking" rules,( until the line was closed at the end of the day), and changed the range rules to prohibit Blowing down the barrel.
It is not unusual for businesses and organizations to adopt more stringent operating rules to limit their liability exposure, even when lesser standards are not going to realistically increase the danger to people involved in activities. The cost, and availability of Insurance motivates organizations to attempt to limit all exposure they can reasonably anticipate, and carry the insurance for that rare case they didn't anticipate. That tends to keep Insurance premiums lower, and for volunteer associations, that becomes critical.
So, put a couple of cleaning jags in your range box, or leave at least one of them screwed to your ramrod. I have one on the rod in the gun, and another on my range rod, that goes in the same gun case with the gun. If the gun makes it to the range :shocked2: , I also have the right jags. Now, where are those cleaning patches.......... :rotf: :thumbsup: