Siegmund Posted July 20, 2010 Share Posted July 20, 2010 (edited) Sooo, there's this standard naming convention based on inside diameters... 3/8" 2oz1/2" 4oz5/8" 8oz3/4" 1lb1" 3lb We are told the names come from the size of lead shot that would fit into the tubes.Up to here it acts as you would expect - double the dimensions, 8x the weight, 25% increase in dimension, approx 2x the weight. Then the pattern changes, and makes you scratch your head: 1-1/4" 4lb (not 6 like you would expect) 1-1/2" 6lb (not 8 like you would expect) ...and then I got to thinking... wow, these aren't remotely close to sizes of lead shot. A one-pound lead ball is 1.67" in diameter. A 10-gauge shotgun (1.6oz lead ball) has a wider bore than a one-pound rocket tube! So, since they are NOT named for the diameters of single balls of lead, what? Is a one-pound rocket tube supposed to be long enough to hold ten lead balls with a total weight of 1 pound (7 1/2")? A cylinder of lead weighing a pound (3/4" wide and 5 1/2" long?) I have no idea... yes, we can just memorize it as an arbitrary convention, but it'd be nice to know why. Edited July 20, 2010 by Siegmund Link to comment Share on other sites More sharing options...
FREAKYDUTCHMEN Posted July 20, 2010 Share Posted July 20, 2010 It's time to use the metric system. Link to comment Share on other sites More sharing options...
Mumbles Posted July 20, 2010 Share Posted July 20, 2010 I've heard all sorts of stuff. The only one that makes sense to me is the mass of lead balls the ID of the tube that will fill the tube, which generally means 10. Anyone who says otherwise has never done the math. I see even very intelligent individuals getting this incorrect. I've seen a single lead ball the ID of the tube, a single lead ball the OD of the tube (which used to be a lot thicker), etc. They're old, archaeic, and are designed for BP only. If you do the math for the lead balls to fill the case, the math works on out on everything fairly closely except for 2lb, 3lb and 6lb. I kind of wonder if the 2/3lb thing is just a man made anomaly. IE the 7/8" size got created and they needed a new name for it. 7/8" should be around 24oz (1.5lb) and 1" is close to 2lb actually. 1.5" in reality is more than 7lbs. I've included my calculated values below based on 11.34g/mL density of lead. It's possible they used different sized tubes than we do of course. 0.375 - 1.81 oz0.5 - 4.29 oz0.625 - 8.37 oz0.75 - 0.91 lb0.875 - 1.58 lb1 - 2.14 lb1.25 - 4.19 lb1.5 - 7.23 lb There are enough pyros in the US who would be more confused by the metric system than this archeic system honestly. Link to comment Share on other sites More sharing options...
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