Caliper_Mi
Member
Just curious: why is it OK on a smokeless powder cartridge to have empty air space around the powder, but black powder must be compressed so there is no empty space?
Air space
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Millwright
Member
Black powder is an explosive. Smokeless powder is a deflagrant. IOW it has to do with how the respective propellants burn, hence generate the "push" needed to propell the bullet ! BP has a stronger initial 'hit' but tapers off rapidly as the bullet exits. Smokeless powders generate a 'stronger/longer push', i.e. 'pressure pulse', due to their coatings and treatments.
FWIW most smokeless loads benefit - in various ways - by the addition of inert fillers to take up the open space. >MW
FWIW most smokeless loads benefit - in various ways - by the addition of inert fillers to take up the open space. >MW
Actually.....it has more to do with bore fouling. Use an uncompressed load in or a b.p. load that has airspace in a cartridge gun and the fouling in the bore is greater than a compressed load.
Regarding airspace in b.p. cartridges, way back when, the factories loaded .45-70 "Short Range" cartridges with 200 gr bullets and 20 grs of b.p. loaded loosely in the case. There was also an "Armory" loading of a 300 gr bullet and 30 grs. of b.p. that was loose in the case.
Back in the 1800's a .45-70 Springfield was used to test various airspaces and as the bullet was seated further and further and further down the bore away from the 70 gr. charge, the pressures became less and less.
More info here.....
http://www.theopenrange.net/forum/index.php?topic=2098.0
w30wcf
Regarding airspace in b.p. cartridges, way back when, the factories loaded .45-70 "Short Range" cartridges with 200 gr bullets and 20 grs of b.p. loaded loosely in the case. There was also an "Armory" loading of a 300 gr bullet and 30 grs. of b.p. that was loose in the case.
Back in the 1800's a .45-70 Springfield was used to test various airspaces and as the bullet was seated further and further and further down the bore away from the 70 gr. charge, the pressures became less and less.
More info here.....
http://www.theopenrange.net/forum/index.php?topic=2098.0
w30wcf
Tommygunn
Member
Never heard that before. Hmmmmm. I always thought it was dangerous to leave an airspace.
Next thing I know I'll find out Sasquatch is real ......
Next thing I know I'll find out Sasquatch is real ......
Fingers McGee
Member
You mean he isn't???? 
Cosmoline
Member
Make no mistake, it IS dangerous. How do I know that? I got to chatting with a fellow at the range last year while loading a .54 smooth rifle. The ball was hung up 2/3rds of the way down, but since I was not paying attention I felt it stop and didn't check my rod mark. As a consequence there was a space between the 75 grains of 3F and the PRB. Did it make a difference? Well the recoil was enough to bruise *MY* ribs and leave me hurting for a week. I've shot some brutal bear guns over the years, and none of them ever did that to me. Thankfully the barrel held, but it was a heck of a way to proof check the barrel.
Exactly why this happens I do not know. But it does happen, and can cause a serious KB.
Exactly why this happens I do not know. But it does happen, and can cause a serious KB.
PRM
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Always heard that there was supposed to be no space in a BP cartridge, may have to rethink this with some more research. Either way, I'd say a cartridge not compressed and a ball hung 2/3 of the way down the barrel is two different things. The barrel issue would classify more as an obstruction. Not uncommon to see a barrel bulged or even burst with obstructions.
BCRider
Member
I suspect that much of it has to do with how fast BP burns. If it's compressed well then the burn will start at the point of ignition and work its way down the stack of powder much like a solid pellet would burn. If there's an air space the turbulence and shock caused by the burning of the initial powder would stir up the loose powder in the rest of the space and it would all burn at once resulting in a huge pressure spike. That likely being what happened to Cosmoline.
If this be so then any air gap is a bad thing. Even only just barely not leaving a gap is just barely adequite since it imples that the powder is loose so it could stir around at least a little. But it sure would not be as bad as powder sitting in a loose layer such as Cosmo' had.
That idea that the compressed stack burns from back to front would seem to be supported by the amount of still burning particles that come out the barrel along with the ball or bullet.
If this be so then any air gap is a bad thing. Even only just barely not leaving a gap is just barely adequite since it imples that the powder is loose so it could stir around at least a little. But it sure would not be as bad as powder sitting in a loose layer such as Cosmo' had.
That idea that the compressed stack burns from back to front would seem to be supported by the amount of still burning particles that come out the barrel along with the ball or bullet.
Yes indeed. A muzzleloader and a cartridge rifle are two completely different animals. Personally, I shoot cartridge rifles and always use compression because I have found it improves accuracy and gives the least fouling.
I have fire many .45 Colt b.p. rounds with powder loaded loosely in the case and lower recoil, lower velocity, increased fouling and less accuracy were the result. Nothing else.
Now here's part of a phamplet from DuPont regarding loading b.p. in cartridges. Note the second paragraph on page 2 regarding airspace...
w30wcf
I have fire many .45 Colt b.p. rounds with powder loaded loosely in the case and lower recoil, lower velocity, increased fouling and less accuracy were the result. Nothing else.
Now here's part of a phamplet from DuPont regarding loading b.p. in cartridges. Note the second paragraph on page 2 regarding airspace...
w30wcf
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