Airspace and Breech Seating?

[RPRNY]

I have a question. Why are we so concerned about not having any airspace in a black powder cartridge when in breech seating with black powder cartridges, I leave 1/16" - 1/8" space between bullet base an powder charge, covered by a milk carton wad?

[Texantothecore]

Ah... the sweet mystery...

[mikeym1a]

That is an interesting question. I always assumed that the neck of the case contacted the base of the projectile. I'm sure someone more knowledgeable will chime in to enlighten us. This is the kind of stuff I look for on this site. Interesting stuff. Thanks for the question. mikey

[curator]

Scientific studies have shown that a SMALL amount of air space in a black powder cartridge is not the bomb "conventional wisdom" claims. Tests with varying amount of empty air space between black powder and projectile showed that as air space increased, velocity decreased. Also, velocity/pressure varied more significantly with more air space. Of course, this is near heresy to the M/L crowd. However, it has been proven that black powder burns most uniformly and efficiently when moderately compressed and air space or loose-filled cartridges have a lot of velocity variation and are less accurate. The Shutzen guys who breech-seat bullets then load cartridges capped with a wad do get a small amount of air space but their powder charge is usually slightly (or more) compressed to give uniform, efficient combustion. A rather extreme analogy compares the burning of a solid fuel rocket and a coal-dust explosion with the compressed load burning in a smooth acceleration at it pushes the bullet down the bore and the loose-filled chamber with air-space igniting non-uniformly or all at once with varying degrees of efficiency.

[Gunlaker]

Airspace of 1/8" is not a problem with any of my breech seated loads with black powder. If you do some digging on the ASSRA forum you'll find a fair bit of info on it. It's also been covered in articles in SPG's magazine. For best accuracy and less case stretching, I've heard of a number of people filling the empty space with a felt wad. I haven't gone there yet.

Chris.

[af2fb751]

Several years ago, a reenactor at Brandywine demonstrated the breech loading rifles (Ferguson?) that were used in small numbers during the Revolutionary War. He fired round after round, rolling a ball in and then dumping 2F in from paper cartridges. He didn't seat the ball on the charge and afterwards said that if the chamber was 70% full, the charge behaved normally. Of course that contradicted the rules as I knew them.

[RPRNY]

Several years ago, a reenactor at Brandywine demonstrated the breech loading rifles (Ferguson?) that were used in small numbers during the Revolutionary War. He fired round after round, rolling a ball in and then dumping 2F in from paper cartridges. He didn't seat the ball on the charge and afterwards said that if the chamber was 70% full, the charge behaved normally. Of course that contradicted the rules as I knew them.

I started the thread so I can hijack it without guilt. The Ferguson rifle has always really interested me. It's one of those "what if Spartacus had had a Piper Cub" type things. It was way ahead of its time and would still have been game changing technology in the War of Southern Miscalculation. Presumably it was complexity and cost of manufacturing that kept it from taking off. I wonder if anybody has made replicas?

[mikeym1a]

I started the thread so I can hijack it without guilt. The Ferguson rifle has always really interested me. It's one of those "what if Spartacus had had a Piper Cub" type things. It was way ahead of its time and would still have been game changing technology in the War of Southern Miscalculation. Presumably it was complexity and cost of manufacturing that kept it from taking off. I wonder if anybody has made replicas?

The King of England was impressed with Col Ferguson's rifle, and authorized the purchase of 10,000 pieces. However, the head of Ordnance, who disliked anything new, moved the punctuation mark, and it read 100.00 pieces, so that was all that Col Ferguson got. It was expensive, and his unit did not survive the war. One can only imagine where those 100 rifles ended up. mikey

[5.7 MAN]

I had a 1859 paper ctg sharps, and loading it with loose powder would always result in an air space. I think in Muzzle loader the dnager comes from a big space say maybe 2-3". l have seen a few threads here about ringing the chamber of a sharps but seems to involve smokeless powder and wads.

[Lead pot]

I will tell you my story on air gaps and you can take it from there
Muzzle loaders and cartridge rifles are two different rifles even though they shoot black powder. I have personally ruined three barrels. One in a muzzle loader with a short seated ball and ended up with a walnut just ahead of the breach plug. The first was a Roller when I was a Kid using a .43 Spanish. At age 14 or 15 that rifle just belted me something fierce so I short loaded the round and ended up bulging the barrel in the chamber portion after several shots where I could not extract the case with out using a cleaning rod. The second rifle I had a hang fire that must have had the primer push the bullet ahead a little and when the charge went off I could not extract the case because of the ring it formed.
A shooter at the range once came over after shooting his .45-120 pedersoli asking me if he could use mu cleaning rod to get a stuck case out. I went with him and looked at the case once he got it out and a shiny bright case neck about 3/4" down from the case mouth where it swaged back down from getting pushed out using the rod told me right what the problem was, a ring. The dark shadow was very plain to see looking down the barrel. I asked him how he loaded the round and he said he cut the powder load back because of the recoil and filled the rest of the case with toilet paper. He said that he has been doing this for some time.

When I breach seat, my wad is flush with the case mouth and when I seat the loaded case it makes contact with the bullet base. I don't know how much of a gap you can get by with before the compressed air between the over the powder wad gets compressed between the bullet edges the bore and deepens that ring enough to get extraction problems.
When I breach seat the high power rifle using smokeless I don't use a fillet or wad to hold the powder back.

LP

[John Boy]

Harry Pope and Doc Hudson filled the case with powder and capped it with a felt wad when breech seating at their many matches. Shooting many thousands of reloads, there has never been any published statements that either shooter ever had a ringed chamber ... with black powder, semi-smokeless or black powder duplex reloads with smokeless powder

Also, on The Open Range many years ago, we discussed this subject with about 20 pages of words including a picture of an 1800's factory round with air space ... conclusion - a rare event resulting from an unknown cause

[bigted]

this subject has always interested me with its varying reports on the phenomenon. it would be very educational to have a truly scientific approach with provable results to squelch this mystery once for all.

some claim that no problems occur and others have bulg's and walnuts that have occured.

is there tests that could be conducted to allow some sort of continuity to this subject? are the bulg's occuring in the old steel chambers/barrels or is the damage happening in modern barrels as well?

be nice to get some definet results so the mystery is negated.

for now tho ... im gonna just ensure that i have NO air space to deal with. seems like the best option for me.

[Lead pot]

Well I still have the barrel with the rung chamber. You can look at it anytime :

[enfield]

Rung, Runged, Or Ringed that cant be good for anybody !

[bigted]

Lead Pot ... i do not doubt you in the least! i was not doubting your experience at all. just some claim that it dont matter and i would like to know why they would make this claim while others ... like yourself ... has had this experience. just makes me wonder is all. i will not allow any air space under any of my bp loads just the same as i really dont want to have your kinda experience ... ever!

[John Boy]

One of the posts on TOR, re: air space
Dan Phariss has an article in this issue of BPC News (Spring 2006) on compression and gives Dutch Bill a paragraph ...
"Having the powder tightly gripping the case walls brings to mind what I was told by William Knight about Dupont's research into blasting powder. The standard practice in breaking rock was to tamp fused black powder in a hole and then apply a clay plug that was also tamped. Much of the force was lost as the plug was blown from the hole like a bullet from a gun barrel. Dupont found then adding a layer of dry sand over the powder, then tamping in the clay plug, greatly increased efficiency. The sand would literally jam in the hole until much higher pressure was obtained. While I do not know if the compressed black powder grips the case walls as the sand did, it certainly seems so when trying to get the powder back out of the die. I am not inferring that this could result in a burst firearm, but then again, I don't know. I am saying that heavy compression would change the burn rate or at least how the powder performs as a propellant."

[Lead pot]

Where a lot of the problem with short loads ruining chambers using black powder is when a wad is placed over the powder with a short load with a air gap between the wad and bullet base or a wad over the powder and the rest filled with toilet paper or a cotton ball under the bullet.

[Don McDowell]

My guess at what happens with a short charge of black in a cartridge case is the neck tension/crimp holding the bullet in and if a wad (usually larger diameter than the bullet) is used then you get a compressed air bulge going on before the bullet can break the crimp and go.
Where the breach seated bullets are already engraved into the rifling, even tho the powder is held in place by the wad at the case mouth, the bullet will start moving easier than one held tighly into the case and having to engrave it's self into the rifling in the short charged case example.
We see sort of the same affect with paper patching to bore, that bullet will generally go across the chronograph slower than a greaser of the same weight, due to the gas escape before the patch gets the bore sealed.

[Lead pot]

Don, and don't forget the now standard 45 degree chamber end transition also holding the bullet back when it expands in the case.

[Don McDowell]

Yup that's what I was thinking about , that poor abused greaser getting violenty slammed into that abrupt beginning of the rifling.
The hard part is imagining how this all happens in a millisecond, sort of like watcthing the knotters on a baler, we know how and why the work, but there's no way it'll work in slow enough motion for the eye to capture it and the mind to process it..