Loading the 577-450


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RecoilRob
July 29, 2008, 11:41 PM
Am about to put powder and ball into cases to make the Martini-Henry MK IV speak for the first time in over 100 years. Have run upon a puzzlement that maybe one of my fellow THR members can help solve.

The modern smokeless powder weights are all based on 7000 grains/lb and are all actually weighed on a scale. Black powder charges are usually referred to in grains by measure...which uses a measuring device made for the powder. But, when set to 85 grains it throws more...by weight than it says it is.

My question: When the old British manuals say the charge was '85 grains', are they actually referring to a volumetric equivalent and NOT the measured weight?

This is my first Black Powder Cartridge loading endeavour and I'm committed to doing it right. Thanks for any help.

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rodinal220
July 30, 2008, 12:06 AM
Volumes of info on 577-450 loading here,real nice folks too.Most RKIs load by weight with the M-H round.Its a unique round with some loading challenges and different from "normal" smokeless reloading.

Use real BP in Fg,especially if using CBC/24g brass.

Its a huge case and a carded wool/cotton(100%)filler should be used.

Make sure you know the correct bore diameter for your rifle so the proper size bullet can be selected.

http://britishmilitariaforums.yuku.com/

Omnivore
July 30, 2008, 12:44 AM
To address the weight verses volume issue; there should be no significant difference, other than that resulting from different lots of black powder, and from settling of the powder, or from different granulation sizes.

That is if we're talking about real black powder. When you get into substitutes, you typically use an equivalent volume to real black powder.

With real BP, we weigh a charge, and then use that same volume as a measure in the field for either real BP or a substitute.

Same goes for modern cartridge loading really-- you set your powder measure by weighing the charges, but after that it's throwing mechanically by volume, simply so you don't have to actually weigh each charge. Some people weigh each charge anyway, for better consistency.

I have a "30 grain" spout for loading BP pistols, but if I weigh the charges, they come out between 26 and 28 grains by weight. It's just a matter of accuracy in manufacture and how consistently I personally can throw a charge, how much my fat finger intrudes into the end of the spout, how much the powder settles with vibration, etc.. Besides all that, I can take several different factory new black powder measures, weigh the charges from each, and they all throw a different weight. I've done it. Some are off by as much as 5 grains on average, or between 5 and 10% depending on total value.

One adjustable measure I tested had a plunger screwed into the graduated rod that had all the values engraved into it. But the plunger was unscrewed a little bit, lengthening the rod, so the charges it was throwing were light by about 5 grains. Stuff like that.

Bottom line is that weighing is more accurate than going by volume. Then we can discuss things that go wrong with your powder scale... Use caution. People blow their guns apart once in a while.

RecoilRob
July 30, 2008, 09:58 PM
Thanks guys! Great link rodinal...much reading to come.

Am going to put up the first batch with 85 grains (weighed) Wano FG. Bullet is a tad light at 410, but that should keep pressures down...as well as it being a 3 grease-groove version vs paper patched.

Really on the fence about fillers and don't want to use them if I can get around it. Best I can tell, they are recommended to keep the wad column from falling into the shoulder area as the stuff used isn't dense enough to make any compression of the powder.

Shouldn't have a problem with the wads I have...060 veggie fibre and quite stiff. They fit tightly in the neck and, once positioned, I'm not imagining them coming loose.

Will run the first handfull without additional fillers I think. Big SPG lube cookie and the stuff in the grease grooves (hopefully) will keep things soft and lubed during the string.

Will keep the THR board advised on the progress (or not!). Dearth of info here on the Martini-Henrys. We need to improve!

Voodoochile
July 30, 2008, 10:46 PM
Like Omnivore said, my 2 measures that I've used for over 24 years for my rifles will accurately throw a charge of 10 - 120gr. & will be within +/-1 grain from the actual weight on the scale when I'm using Goex Black Powder "I guess I'm that lucky with my hands" but any Sub will be lighter in weight.

Good luck in your loads & I can't wait for a range report from that beast from the past. :D

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