Portugiserne slår franskmennene i slaget ved Rio de Janeiro. Kampene var konsentrert rundt fortet Uruçú-mirim. Den portugisiske kommandanten Estácio de Sá ble truffet av en pil i øyet under slaget, og døde en måned senere. Bakgrunnen var... Read more ...
Slaget ved Rio de Janeiro
Portugiserne slår franskmennene i slaget ved Rio de Janeiro. Kampene var konsentrert rundt fortet Uruçú-mirim. Den portugisiske kommandanten Estácio de Sá ble truffet av en pil i øyet under slaget, og døde en måned senere.
Bakgrunnen var at 500 franske kolonister under ledelse av den franske admiralen Nicolas Durand de Villegaignon okkuperte en av øyene i Guanabarabukten i 1555, som nå heter Villegagnonøya. Han fikk der bygget Fort Coligny som et ledd i opprettelsen av den franske kolonien France Antarctique.
Selve byen Rio de Janeiro ble grunnlagt av portugiserne 1. mars 1565. Byen ble grunnlagt som en base for å forberede en invasjon av den franske bosetningen, noe som ble gjort i 1567. Inntil tidlig i det 18. århundre ble byen truet eller invadert av flere, for det meste franskmenn, pirater og sjørøvere.
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The Martini-Henry rifle was the British military service rifle from the end of the 1880\'s. It served on all continents and was a powerful and reliable rifle. This article is the first part in a series of two on the Martini-Henry rifles. This part deals about the background history of the Martini-Henry rifles.
Published: 24 November 2007 by Øyvind Flatnes.
Edited: 14 September 2008.
Old myths can sometimes be hard to get rid of. Within the black powder sport there's also a few "truths" that shooters seem to assume are right. One example is the so called chainfire or multiple discharges in percussion revolvers. Many shooters believe that the chainfires are caused by to little or no grease over the balls in the chambers and that flames from a fired shot can pass the ball in a second chamber and ignite the powder thus causing a chain reaction. The result can be both unpleasant and dangerous, but I haven't heard of any serious injuries to shooters caused by chainfires.
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You can learn more about the safe practical use of the percussion revolver in the brand new book From Musket to Metallic Cartridge: A Practical History of Black Powder Firearms.
I decided to try to prove that frontal chainfires virtually is impossible if the revolver is loaded the right way and started a small experiment. I used the cylinder on my 1858 Remington New Army .44 cal. First, I took the cylinder off the revolver and then bolted it on a large steel plate.The way I did it: I threaded a bolt all the way down to its head, drilled a hole for it in the plate and fastened the bolt with a nut. The bolt was just large enough so that I could slip the cylinder from my revolver over it and lock it with another nut. What I had was a cylinder bolted on a large steel plate.
The experiment was simple: I would try to provoke a chainfire from a chamber in a cap and ball revolver. I loaded one of the chambers in my Remington with 25 grains 3F black powder and a cast .454" roundball with no filler, wad or bullet lube in front of the ball. My intention was to make the round ignite from the "outside", in other words, make a flame pass the lead ball and ignite the main charge. I filled 3F black powder in front of the ball, made a fuse and lit it. Nothing happened except that the powder in front of the ball ignited. I tried this nine more times, and still the same results. For every second try I loaded a new ball. When nothing happened with the ten first I decided to go try a smaller .451" ball. I used exactly the same procedures. The .451" balls entered the chamber easily and I didn't have to use much pressure on the rammer to seat the balls. But still the main charges wouldn't ignite. The next day I tried some more variations. I loaded a .451" ball, loaded with the sprue to the side of the chamber wall and lit the fuse. Still no discharge after ten more attempts. I tried twenty more attempts, but still no discharge.
Then what is causing the multiple discharges? Probably loose fitting caps. If you drop a cap from the nipple of a loaded chamber there will be a large amount of flames around the nipple area when a shot is discharged. Some of these flames can find its way into the channel of an uncapped nipple and cause a chainfire. If you doubt this you can take a look at the small touch hole of a flintlock and the hot flame a percussion cap can make. It's pretty much the same principle. If you have an uncapped loaded chamber on a revolver while shooting you have, in my opinion, a bomb in your hand.
Then it was time to try to ignite the round from the opposite side of the cylinder: I loaded a .451" ball with no filler, wad or grease and put a small amount of 3F black powder on the neighbour chambers nipple area and lit the fuse. I did not put a cap on the nipples. Nothing happened, until I lit the fuse the 9th time. The loaded chamber went off with a bang.
But it isn't loose fitting caps only that can cause multiple discharges. If the nipples are too long the recoil can drive the cylinder back against the recoil shield and detonate the other caps. Perhaps this is the most likely explanation when several or all chambers ignite at the same time? Anyway, if you replace your nipples you should be aware of this. If they are too long you can easily file them shorter.
I don't know how much I should emphasize on this little experiment, but I'm pretty sure that people should pay more attention to the caps when shooting cap and ball revolvers instead of fill their chambers with grease. The flame from the cap is very hot and I believe most of the multiple discharges are caused by loose fitting caps. I'm not saying that the flame couldn't pass the ball and ignite the main charge though. In theory it could happen, but if you use a correct size ball the chances should be minimal. The .451" ball combination in my Remington chamber was quite loose, and I didn't have to use much force on the rammer but the seal seemed to be good enough. Perhaps the flame from a chamber that has been ignited is hotter than the loose powder in front of the balls that I used in my experiment, but anyway, I think the frontal chainfire theory has to be buried once and for all.
Note: After some criticism regarding my methods during this experiment I made another one. The following is an excerpt from my post on the MLAIC mailing list which originally criticised my methods:
“Now I've spent some days doing some more experiments. As I regard the theory of ignition through the nipples as obvious, I have focused on getting frontal ignition from a loaded cylinder. I won't call the cylinder "properly loaded", because I think the .451" bullets I used in the experiment fit too loosely. I normally use a .454" ball. I went on to use my .44 Uberti Remington and loaded one chamber full of FFFg Wano powder and put the bullet on top with no wad, grease or similar. The loaded ball was flush with the chamber mouth.
Then I tried to set the charge off by shooting sparks past the ball and in to the powder. This was done by shooting various compressed charges into the loaded chamber from the side from about 8-10 cm distance. I started off with twenty 16 gauge shotgun shells that was roll crimped with two card discs below 50 grains of FFFg Wano for the ten first shells and 70 grains of KIK blasting powder for the ten next. I also used blanks from a .577.450 Martini-Henry, a .44 cal. percussion revolver and a .44 cal. muzzleloading pistol. All in all I fired 50 shots with no ignition of the cylinder. Before the last 20 shots I poured a small amount of FFFFg powder over the ball. After every second shot the ball in the cylinder was shot out and I reloaded with a fresh ball and powder. I did not get any frontal ignition.
Just to try to get a multiple discharge I loaded all six chambers with 30 grains of FFFg Wano and put a wad lightly greased with Bore Butter on top. Then I capped the revolver and the blanks without getting any frontal ignition when I shot them. I proceeded with the same load, but this time I put a ball in every second chamber. I capped all six chambers and fired the balls only. The chambers only protected by a felt wad did not go off. I then loaded the cylinder ditto, except this time I loaded the chambers without balls to the brim with powder before I put a felt wad over. The wad was in other words flush with the chamber mouth. This time I finally got to experience a frontal ignition. It happened as I fired the second ball. After I had fired all of the three chambers loaded with ball two of the felt loaded chambers were still in place.
I have spent more than a few moments of thinking, experimenting and collecting information, both historical and modern, on this subject, and here are my views in a short version:
1. You will probably not experience a multiple discharge:
- if the ball is of correct size and is perfect without damages or wrinkles.
- if the caps are tight and don't get lost while shooting.
- if you use correct size nipples.
- if you seat the caps on the nipples.
- if the nipples are securely tightened to the cylinder.
2. You are in danger of having a multiple discharge:
- if the balls you are using are too small or are damaged/wrinkled.
- if you have a heavily pitted chamber.
- if you keep loosing caps while shooting.
- if you have too long nipples, perhaps in combination with either:
- a. caps that are not seated on the nipples or
- b. nipples that are not properly fastened (it makes them longer, same as a).
- if you ignore the other points and depend on greased chambers to prevent any chainfire. If you do this you are in danger of being nominated to the Darwin Award."
Remember: If you have loose fitting balls in your percussion revolver grease over the chambers will do nothing to prevent chainfires. The grease is blown away at the first shot anyway and if the ball combo is loose enough for a spark to pass it, well, no grease will prevent it from doing it. Use proper fitting balls!