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Old 04-22-2021, 12:19 AM   #1
Tomsdad
 
Join Date: Jan 2010
Location: Brighton
Default French C19th mitrailleuse

Hi

has anyone seen or done a write up of the various versions of the mitrailleuse?

Or can point me in the direction of it in a GURPS publication (I thought it was in a pyramid, but I can't see it, and while it's mentioned a few times in threads here AFAICT it's not stated up)

A lot of stuff like weight, capacity etc I can take from places like the wiki, but what would be cool is people's takes on:

ROF while it's being fired and the reload time for each new block of ammunition. The fact that it cites a usual continuous rate of 100 (including 4x reloads in 1 min) with a trained crew but in emergencies 125 (5x reloads) suggests to me the main limiting factor is the reload and the crew not so much the mechanical top speed of the crank and the firing. Although that would still limit ROF while firing. Either way a good candidate for fast loading skills/techniques etc

Also anyone got any idea of the GURPS stats of the cartridge as it's not the usual Chasspot or Dreyse. apparently:

It was rather similar to an elongated modern shotgun shell: centerfire with a rimmed brass head and a dark blue hardened cardboard body.[7] The 770-grain (50 g), 13 mm (0.512 inch) patched bullet was propelled by 185 grains (12 grams) of compressed black powder at a muzzle velocity of 1,560 ft/s (480 m/s), three and a half times more powerful than Chassepot or Dreyse rifle ammunition


Sorry I'm not very good at the various ballistics worksheets used by posters here!

Stuff like the triple rounds mentioned can be done with the HT rules

anyway

cheers

TD
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Last edited by Tomsdad; 04-22-2021 at 01:58 AM.
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Old 04-22-2021, 06:43 AM   #2
Anaraxes
 
Join Date: Sep 2007
Default Re: French C19th mitrailleuse

This demo shows the discharge of all 25 barrels in five seconds, or occasionally a bit longer. So, for mechanical purposes, RoF 5.

That really depends the speed at which the gunner spins the crank, and he doesn't seem to be working that hard, so I'm sure you could push it up a bit. But obviously the gunner knows the GURPS rules well, and is satisfied to just reach the breakpoint of 5 for a +1 to hit and also qualifying for suppression fire. Getting all the way to 9 would mean spinning that crank twice as fast. Maybe not impossible, but it'd be a lot harder if there's any mechanical resistance. And purely from convenience, 5 is a nice value to use with a 25-round magazine.

Alas, that video doesn't show the reloading process. There are some other animations; basically, it's dropping a pre-loaded plate into the breech and securing it with a lever. So, it's like loading a magazine, a reload time of "N" for all rounds rather than "Ni" (individual rounds). If we take Wiki at its word, then 4 volleys per minute means 10 seconds to reload (15 seconds to reload and fire). The "urgent" rate of 5 volleys means 7 seconds to reload (12 to reload and fire). One cited advantage is the weight of the gun and carriage meaning no need to resight the weapon, so we can take that all as the time to get the new magazine plate into plate. So Reload 7-10, and I'd probably assume the 7 seconds includes successful Fast-Draw rolls, so the base value would be higher than 7.

Inserting 25 cartridges into a spare breech plate would be a lot like loading a revolver, probably a little easier than pushing cartridges into a spring-loaded box magazine. Just dropping cartridges into holes. 3i seems to be traditional there, maybe as high as 5i since it's so regular and easy access, for 5 seconds to refill a plate. That's as fast as the reload time between volleys, so one of the crew can keep a spare plate filled while the other is loading.

Crew of two is probably sufficient, but I didn't research the historical number. It'd also be interesting to know the French doctrine for number of magazine plates issued per gun, along with how many rounds, as well as the official crew size. (There might well be more men in the unit than strictly necessary just to fire the weapon for additional labor and replacements, as with conventional artillery.)
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Old 04-22-2021, 07:17 AM   #3
Tomsdad
 
Join Date: Jan 2010
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Default Re: French C19th mitrailleuse

Quote:
Originally Posted by Anaraxes View Post
This demo shows the discharge of all 25 barrels in five seconds, or occasionally a bit longer. So, for mechanical purposes, RoF 5.

That really depends the speed at which the gunner spins the crank, and he doesn't seem to be working that hard, so I'm sure you could push it up a bit. But obviously the gunner knows the GURPS rules well, and is satisfied to just reach the breakpoint of 5 for a +1 to hit and also qualifying for suppression fire. Getting all the way to 9 would mean spinning that crank twice as fast. Maybe not impossible, but it'd be a lot harder if there's any mechanical resistance. And purely from convenience, 5 is a nice value to use with a 25-round magazine.

Alas, that video doesn't show the reloading process. There are some other animations; basically, it's dropping a pre-loaded plate into the breech and securing it with a lever. So, it's like loading a magazine, a reload time of "N" for all rounds rather than "Ni" (individual rounds). If we take Wiki at its word, then 4 volleys per minute means 10 seconds to reload (15 seconds to reload and fire). The "urgent" rate of 5 volleys means 7 seconds to reload (12 to reload and fire). One cited advantage is the weight of the gun and carriage meaning no need to resight the weapon, so we can take that all as the time to get the new magazine plate into plate. So Reload 7-10, and I'd probably assume the 7 seconds includes successful Fast-Draw rolls, so the base value would be higher than 7.

Inserting 25 cartridges into a spare breech plate would be a lot like loading a revolver, probably a little easier than pushing cartridges into a spring-loaded box magazine. Just dropping cartridges into holes. 3i seems to be traditional there, maybe as high as 5i since it's so regular and easy access, for 5 seconds to refill a plate. That's as fast as the reload time between volleys, so one of the crew can keep a spare plate filled while the other is loading.

Crew of two is probably sufficient, but I didn't research the historical number. It'd also be interesting to know the French doctrine for number of magazine plates issued per gun, along with how many rounds, as well as the official crew size. (There might well be more men in the unit than strictly necessary just to fire the weapon for additional labor and replacements, as with conventional artillery.)
Cheers, excellent Edit: forgotten weapons I should have known to look there! (That dog's living life dangerously!)

I have to say I was assuming a crew of 3 or 4 (given the size of the thing, the nature of the reload, getting blocks ready prior to reloading the gun). I'd assume they'd have several spare blocks and at least one of them just filling them with cartridges.

anyway ROF 5 would mean 5 seconds to fire off a block 25


so for that continuous 100 a minute it would be 20 seconds to fire the total rounds, leaving 40 seconds to reload 4x, so 10 seconds a reload.

I can see a quick reload roll to shave a couple of seconds off each time, and maybe the crank is worked at a higher ROF rate (6-7) to allow the 5th reload and the extra block to get fired off quicker to get you to 125 in 60 seconds.
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Last edited by Tomsdad; 04-22-2021 at 07:50 AM.
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Old 04-22-2021, 07:33 AM   #4
Anaraxes
 
Join Date: Sep 2007
Default Re: French C19th mitrailleuse

Quote:
Originally Posted by Tomsdad View Post
I have to say I assuming a crew of 3 or 4 (given the size of the thing, the nature of the reload, getting blocks ready prior to reloading the gun)
Reasonable, I think.

I notice on second glance the Wiki article says a crew of six. At least one of those is likely handling the horses to tow the carriage (probably away from the front line). This picture shows five, for a horse artillery model. Lots of images with fewer crew, but they're mostly illustrations, and of course even photos show what the photographer wanted in his image, not necessarily detailed documentation.

Also, the spec may be for what we'd call a fire team. I ran across a slightly later photo of a French Hotchkiss machine gun (also "miltrailleuse") squad of 7, certainly not all necessary as crew. So some of those six might be expected to be riflemen, while two or three are actively engaged with just the main weapon.
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Old 04-22-2021, 07:40 AM   #5
Tomsdad
 
Join Date: Jan 2010
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Default Re: French C19th mitrailleuse

Quote:
Originally Posted by Anaraxes View Post
Reasonable, I think.

I notice on second glance the Wiki article says a crew of six. At least one of those is likely handling the horses to tow the carriage (probably away from the front line). This picture shows five, for a horse artillery model. Lots of images with fewer crew, but they're mostly illustrations, and of course even photos show what the photographer wanted in his image, not necessarily detailed documentation.

Also, the spec may be for what we'd call a fire team. I ran across a slightly later photo of a French Hotchkiss machine gun (also "miltrailleuse") squad of 7, certainly not all necessary as crew. So some of those six might be expected to be riflemen, while two or three are actively engaged with just the main weapon.
Yeah I think you are right, this thing's going to have plenty of infrastructure to go with it to deploy it, and move it around. Especially as it was embedded in with and used as artillery. The way it worked is pretty labour intensive I'd say.

Bit of a dead end especially once the Gatling gun turns up, but still a cool one.

I wonder if it had been used better in 1870/71 it may have gotten a better reputation and thus more leeway for further development. (still hard to compete with the Gatling gun)
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Last edited by Tomsdad; 04-22-2021 at 08:06 AM.
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Old 04-22-2021, 11:11 AM   #6
Anaraxes
 
Join Date: Sep 2007
Default Re: French C19th mitrailleuse

A brief article article from Wargamer Illustrated which might be interesting. It gives the weight of the piece as 350 kg (so, about 20% heavier than the 4-pdr gun with a crew of 8 from Napoleonic times), so six men isn't unreasonable just for schlepping it around. Also, the article describes the ammo supply:

Quote:
Originally Posted by THE MITRAILLEUSE IN THE FRANCO-PRUSSIAN WAR
It was charged by inserting a block of 25 preloaded rounds. which were then fired consecutively in a burst by rotating a handle. The maximum sustainable rate of fire was five such bursts a minute. Muzzle velocity was 475 metres per second (compared to 403 m.p.s. for the Chassepot, which was itself regarded as having an impressively flat trajectory). Each gun was allotted a front-line supply of 418 blocks, of which 81 were carried on the limber, the remainder being in the ammunition waggon
That sounds like the magazines ("blocks") were all pre-loaded and supplied in plenty. So our 7-10s load time is probably the time it takes to grab a block off the limber and get it locked in the breech. Reloading the blocks seems like an out-of-combat activity back at the depot. I'm sure that could be done in the field, but if the ammo wagons have stacks of ready blocks rather than cases of loose cartridges, why would you?

At least one of those crew members probably spends some time running back and forth to the ammo wagon, rather than reloading blocks.
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Old 04-22-2021, 11:00 PM   #7
Tomsdad
 
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Default Re: French C19th mitrailleuse

Quote:
Originally Posted by Anaraxes View Post
A brief article article from Wargamer Illustrated which might be interesting. It gives the weight of the piece as 350 kg (so, about 20% heavier than the 4-pdr gun with a crew of 8 from Napoleonic times), so six men isn't unreasonable just for schlepping it around. Also, the article describes the ammo supply:

That sounds like the magazines ("blocks") were all pre-loaded and supplied in plenty. So our 7-10s load time is probably the time it takes to grab a block off the limber and get it locked in the breech. Reloading the blocks seems like an out-of-combat activity back at the depot. I'm sure that could be done in the field, but if the ammo wagons have stacks of ready blocks rather than cases of loose cartridges, why would you?

At least one of those crew members probably spends some time running back and forth to the ammo wagon, rather than reloading blocks.
Yes I think you are right, truth to tell I think I had the wrong idea in my head of what I thought the blocks/breech plates were (I thought they were bigger and heavier, making having large numbers of them harder).
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Last edited by Tomsdad; 04-23-2021 at 04:15 AM.
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Old 04-23-2021, 01:44 AM   #8
johndallman
 
Join Date: Oct 2010
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Default Re: French C19th mitrailleuse

Quote:
Originally Posted by Anaraxes View Post
Inserting 25 cartridges into a spare breech plate would be a lot like loading a revolver, probably a little easier than pushing cartridges into a spring-loaded box magazine. Just dropping cartridges into holes. 3i seems to be traditional there, maybe as high as 5i since it's so regular and easy access, for 5 seconds to refill a plate.
Loading time of 3i is three seconds per individual round. So loading a 25-round plate would take 75 seconds. You might get it down to 2i, for 50 seconds, but a supply of pre-loaded plates is a necessity for a high rate of fire.
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Old 04-23-2021, 05:30 AM   #9
Anaraxes
 
Join Date: Sep 2007
Default Re: French C19th mitrailleuse

Quote:
Originally Posted by johndallman View Post
Loading time of 3i is three seconds per individual round.
Yes. I don't know where my head went when I wrote that, dividing instead of multiplying.
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Old 04-23-2021, 05:52 AM   #10
Sam Baughn
 
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Default Re: French C19th mitrailleuse

According to Wikipedia, the Reffye mitrailleuse shot a 13 mm 50 gram bullet at 480 meters per second. That's a kinetic energy of 5,760 Joules.

My simplified version of the gun damage formula is:

( (a^(1/2)) / (b)^(1/3) ) c = d

Where a is kinetic energy in Joules, b is bullet diameter in mm, c is the arbitrary constant 0.23, and d is damage in dice.

That says it should do 7d+1 pi+. Using the more complicated equation from Interior and Terminal Ballistics for GURPS, I think it is slightly higher, around 7d+3 pi+. Either way, it's a lot of damage for the time.
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