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Weighed VS Volumetric Charges

1669 Views 4 Replies 3 Participants Last post by  Wes Ramsey
When I scale weighed my charge of Triple 7, I found the weighed charge was more powder then my old graduated powder measure tube was giving me.

Do you folks normally weigh your loads?

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Volume only with that replica powder!!! As you've discovered's a whole lot lighter powder.
I weigh mine for my blackpowder cartridges and pre-measured vials for my muzzleloaders...but I'm shooting real blackpowder.
Black powder substitutes are designed to provide roughly the same charge as black powder by volume - not by weight. Since the last couple of threads on this I've done some reading on the topic. All BP and substitutes will weigh fewer grains than they will measure by volume. Back in the day, nobody carried a scale with them so they had to measure by volume in whatever brass or horn tool they had available. It's just the way its always been. Now, for improved accuracy you can weigh BP charges, but ONLY IF you first figure out the equivalent weight by volume. In other words you have to measure by volume an appropriate charge for your ML (say 100 grains), then weigh that charge - it might come out to 68gr or 75gr. I don't know. You'll have to do this for each different bottle of powder, but for the ultimate in accuracy it may be worth it. Just don't expect volume charge grains to be = to weighed charge grains.
Weighing the charge then putting into a premeasured charge kit is the way I want to go in the field.

I found this online:

From the Hodgdon's web site, Triple 7 Loading Notes:

"All charges of Triple Seven or Pyrodex should be measured by VOLUME not weight. A simple, adjustable blackpowder measure is the correct tool for this job. All loads listed in this brochure are measured by VOLUME.

Triple Seven is a high energy product designed to provide the muzzleloading hunter with higher velocities when used in the same VOLUME as blackpowder. To duplicate a blackpowder load velocity using Triple Seven, you must decrease the powder charge by 15%.

Pyrodex is lighter in weight than blackpowder and weighs only about 70% as much as blackpowder. However, because Pyrodex yields more energy per pound than does blackpowder, the same volume of Pyrodex gives similar performance to blackpowder. Pyrodex loads given in this manual for muzzleloading guns are measured by volume, not weight."

It would appear at first blush that 15% less Triple 7 by weight, and 30% less Pyrodex by weight, would duplicate black powder performance. Conversely, 100 weighed grains of Triple 7 would equal 115 weighed grains of black powder, but I'm not sure the pressure curve would remain the same with the heavier charge.

Does this make sense?
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Here's what I would do. Shoot the gun using a MEASURED VOLUMETRIC charge of your choice black powder depending on your personal criteria, i.e. heavy charge for higher velocity or moderate charge for accuracy. Your call. Stick to the thresholds for your specific rifle - if it says don't go over 120gr loose powder, that should be your volumetric max. Get your load tuned where you want it, then measure that volumetric charge by weight. Might even weigh 3-5 different volumetric charges to get an average weight. That should tighten up your groups a little, but don't expect magic. It would also be a good idea to weigh your min and max volumetric charges so you know what your weight range will be, and DO NOT exceed that. I personally don't find that shooting max loads yields acceptable accuracy, but opinions vary.

Keep in mind that different brands of powder will have different WEIGHTs by volume. Never assume that a weighed 65gr charge of Pyrodex RS is = a weighed 65gr charge of 777. The same goes for granule size. 65 weighed grains of FFg DOES NOT = 65 weighed grains of FFFg. If you're using FFg, 120gr is about the max you can go before you're just blowing unburned powder out the barrel. FFFg burns faster, so a 150gr charge may actually get a complete burn before the bullet leaves the barrel, so pressure is higher and more risky to work with. Even if they're the same brand they still burn differently and should be treated accordingly.

All these things to consider is the reason that BP manufacturers only recommend measuring by volume. Whatever your reason for wanting the utmost in accuracy, just be careful what you do, learn your min/max charge weights and stay inside that range. Also keep in mind that it's just a muzzleloader. It was designed to kill big game at relatively short ranges where extreme accuracy is not critical. It wasn't designed to be sub-MOA, and most BP guns would never reach that goal no matter the care you take in choosing and measuring components. Regardless, good luck, good hunting, and let us know if you try it and how much better your groups are when you compare volumetric vs weighed charges :up:
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