a 'deisel accident'.........

[oltom]

Please tell me why we use a thumbstall on loading our pieces?...this months muzzleloading issue has article about a AD with a flintlock, and our cannons are same type of frount loaders.....IF a 'diesel' action could happen with a 'vaccum inside a bore with small powder, as in the article....wouldn't  a thumbstall use on loading cause the same to happen when shoveing powder charge in???
i have never really understood thumbstall use....but a stay with orders of safety and do use it on my 2-14" bore.....

someone tell me in simple terms WHY we do this?

[Cannoneer]

The reason for sealing the vent with a thumbstall is to prevent the "fanning" of oxygen over any live embers that might remain in the bore after firing. 

[Cat Whisperer]

The reason for sealing the vent with a thumbstall is to prevent the "fanning" of oxygen over any live embers that might remain in the bore after firing.

That's the normal-people reason for using it.  I use it to keep the powder from being blown back up into the flash-hole and all over the ground.

[Will Bison]

I don't use a thumb stall. When I wet sponge after discharge the sponge is sloppy wet and water comes gushing out the vent. Not much chance of embers surviving.

[Double D]

Doesn't dieseling require pressure?  It would seem that it would require a lot more effort to get adequate pressure in a flinchlock and even  more in a cannon to get the dieseling effect..

I am more inclined to believe the flinchlock accident was product  of ember fanning from lack of a thumbstall, although with out the details of the flinchlock incident that is really speculation.....

[oltom]

Doesn't dieseling require pressure?  It would seem that it would require a lot more effort to get adequate pressure in a flinchlock and even  more in a cannon to get the dieseling effect..

I am more inclined to believe the flinchlock accident was product  of ember fanning from lack of a thumbstall, although with out the details of the flinchlock incident that is really speculation.....

it seemed the fellow dumped the powder out of the barrel...then wet patched a cleanning patch into the barrel between rounds....then later, started to 'clean' the barrel out strokeing said wet patch. the touch-hole maybe blocked itself with crud, and a few grains ignited under the wet patch sealing and as he stroked it fast and hard...the vacuum and pressure 'dieseled' the few grains and popped the rod out!
i wet spong then dry spong then exaimine my 2-1/4" bore each shot.........and all powder is foil wraped......and i use a off-set rammer to seat powder and shot......i like my right hand, and don't wanna loose it!
but loading a flinter, my rammer is ALWAYS in my hand, and a ball behind it....and the vent IS NOT thumbstalled....makes me wonder!!!

[Artilleryman]

If he wet patched between rounds and didn't dry the bore, some powder may not have ignited.  When he pumped the cleaning rod it may have fanned an ember in the unburned powder and set what was left off.  I don't think it was due to dieseling.

[jamesbeat]

I find it impossible to believe that you could get dieseling to occur with a mop and a thumbstall.
There's just not enough pressure there.

[flagman1776]

 
   
 

[Cannoneer]

flagman1776 makes an important safety point; if you're going to really soak the bore when you wet swab, then you should thoroughly dry mop to soak up all that water before reloading.

[jamesfrom180]

Ordinance barrels should be means of design less "tight".  I have yet to have a rifle flinter or cap AD on loading.  I have seen the consequences of an ember setting a charge off.  What was left of the thumb was pretty scaring for me as a kid.  That said I have started primitive fires with pistons and it really does surprise me how little compression it takes to start tender.  I would guess thumb-stalling mainly keeps embers down in the bore for the wet mop to pick up. 

[subdjoe]

flagman1776 makes an important safety point; if you're going to really soak the bore when you wet swab, then you should thoroughly dry mop to soak up all that water before reloading.

There was a report by the US Ordnance Dept. I think it was 1863, addressing the issue.  The problem was premature ignition and they found that the likely cause was using too wet a sponge.  Too wet increased the chance of unburned powder collecting in the bore and possibly holding a spark. 

The recommendation was that the sponge should be damp, not soaked, and that better to use a dry sponge rather than too wet a sponge.

Do a search of this forum, I think the discussion was about this time last year.  There may be a link to the report. 

[flagman1776]