walt1980 Posted November 3, 2013 Report Share Posted November 3, 2013 I may be completely wrong but as I understand it, a .243 calibre is 0.243 of 1 inch. Surely this is a metric measurement (0.243) of an imperial measurement (1")?? As I said I may be wrong, anyone shed any light on why this is the way it is?! It came up in the pub last night and got us all thinking! Quote Link to comment Share on other sites More sharing options...
Floating Chamber Posted November 3, 2013 Report Share Posted November 3, 2013 (edited) 0.243" Edited November 3, 2013 by Floating Chamber Quote Link to comment Share on other sites More sharing options...
sitsinhedges Posted November 3, 2013 Report Share Posted November 3, 2013 Thousandths of an inch isn't metric. Quote Link to comment Share on other sites More sharing options...
Floating Chamber Posted November 3, 2013 Report Share Posted November 3, 2013 I think he meant 'decimal'. Quote Link to comment Share on other sites More sharing options...
Floating Chamber Posted November 3, 2013 Report Share Posted November 3, 2013 (edited) Metric and decimal are two different ways of expressing EQUIVALENT amounts. An INCH was an inch in many countries until 1789 when the FRENCH created a simpler method of measuring using a measure or 'metre'. It is based on an increment of the distance from the North Pole to the Equator. From this 'metre' and, using pure water to calibrate volumetric and mass units, came THE METRIC SYSTEM. Some folk* still cannot get their heads round it and STILL prefer to use IMPERIAL units. * these are called dinosaurs. I suppose I am a bit of one because I prefer to use 15.432 grains instead of one gram!! Edited November 3, 2013 by Floating Chamber Quote Link to comment Share on other sites More sharing options...
njc110381 Posted November 3, 2013 Report Share Posted November 3, 2013 I kind of get it. Generally a decimalisation of an imperial unit isn't quite right. Trouble is the best fraction you can come up with is .243/1000 (unless someone brighter than me would care to enlighten me?) so the decimal is a better option! Quote Link to comment Share on other sites More sharing options...
sitsinhedges Posted November 3, 2013 Report Share Posted November 3, 2013 It's quite amusing watching young people go into an almost trance like state when asked to measure something in imperial such as eleven and five sixteenths, gazing at their tape measure and wondering what the hell is that Quote Link to comment Share on other sites More sharing options...
njc110381 Posted November 3, 2013 Report Share Posted November 3, 2013 Luckily I'm not that young. As you're older, would you care to come up with the best fraction for this situation? Quote Link to comment Share on other sites More sharing options...
sitsinhedges Posted November 3, 2013 Report Share Posted November 3, 2013 I've never really understood why these various calibres have to be such apparently random sizes. Why not just round them up or down to say .250, 1/4". Does a few thou make that much difference? Quote Link to comment Share on other sites More sharing options...
njc110381 Posted November 3, 2013 Report Share Posted November 3, 2013 Probably not. But if it bothers you you could always buy the sizes that suit! Some of them make sense when turned metric. The .243 being one of them. Quote Link to comment Share on other sites More sharing options...
walt1980 Posted November 3, 2013 Author Report Share Posted November 3, 2013 I get metric and imperial sizes, just seems odd to mix the 2 and wondered if there was a reason for it! Quote Link to comment Share on other sites More sharing options...
Floating Chamber Posted November 3, 2013 Report Share Posted November 3, 2013 Actually it's 243/1000" You drop the point as the /1000 replaces it. The French use a comma to show the partition between whole numbers and increments. Where we use, say, 10.4mm, the French use 10,4mm. The comma in our 'One thousand' (1,000) has now been dropped and is now 1000. Example: 1,000 metres to us would mean ONE METRE on the continent. I had a difficult time as a Maths Teacher when teaching The Metric System and received many letters and phone calls from parents, complaining that I was confusing their kids! I had to remind them it was my duty and THE LAW. Quote Link to comment Share on other sites More sharing options...
sitsinhedges Posted November 3, 2013 Report Share Posted November 3, 2013 Probably not. But if it bothers you you could always buy the sizes that suit! Some of them make sense when turned metric. The .243 being one of them. What does it become? Quote Link to comment Share on other sites More sharing options...
Beretta28g Posted November 3, 2013 Report Share Posted November 3, 2013 well its supposedly .236 so not legal Quote Link to comment Share on other sites More sharing options...
Sprags Posted November 3, 2013 Report Share Posted November 3, 2013 6mm Quote Link to comment Share on other sites More sharing options...
njc110381 Posted November 3, 2013 Report Share Posted November 3, 2013 What does it become? Well 6mm on the packaging. I've never measured a bullet though to see whether it's 6mm or .243? Actually it's 243/1000" You drop the point as the /1000 replaces it. Don't be a smart ***! Quote Link to comment Share on other sites More sharing options...
sitsinhedges Posted November 3, 2013 Report Share Posted November 3, 2013 6mm 25.4 x .243 = 6.1722 Quote Link to comment Share on other sites More sharing options...
Sprags Posted November 3, 2013 Report Share Posted November 3, 2013 Well it says 6mm & .243" on my A-max boxes. But I'll leave the debate to the experts!! Quote Link to comment Share on other sites More sharing options...
Floating Chamber Posted November 3, 2013 Report Share Posted November 3, 2013 Well 6mm on the packaging. I've never measured a bullet though to see whether it's 6mm or .243? Don't be a smart ***! This was not my being sarcastic or a smartie; it was to show how easy it is to confuse someone. The .243/1000, left as it is here is ONE THOUSAND TIMES SMALLER THAN .243 Quote Link to comment Share on other sites More sharing options...
njc110381 Posted November 3, 2013 Report Share Posted November 3, 2013 'Tis true... I have a nasty habit of getting it wrong when I try to be clever! Quote Link to comment Share on other sites More sharing options...
sitsinhedges Posted November 3, 2013 Report Share Posted November 3, 2013 'Tis true... I have a nasty habit of getting it wrong when I try to be clever! That's my trick Quote Link to comment Share on other sites More sharing options...
Blunderbuss Posted November 4, 2013 Report Share Posted November 4, 2013 (edited) I get metric and imperial sizes, just seems odd to mix the 2 and wondered if there was a reason for it!I don't see how they are mixing them? .243, ( or 'point 243 of an inch') is simply an imperial measurement, expressed as a decimal. Prior to us adopting the metric system the use of thousandths (or ten thousandths) of an inch was common, particularly in engineering. As has already been said, you could express it as 243/1000 or 243 thou, but they are a bit of a gob full. .243 is much easier. It gets confusing in other ways though. As already said some calibers are measured across the lands and some across the grooves. Some are nominal, nowhere near the true caliber - .303 (.311) and .38 special (.357) spring to mind. Edited November 4, 2013 by Blunderbuss Quote Link to comment Share on other sites More sharing options...
Blunderbuss Posted November 4, 2013 Report Share Posted November 4, 2013 And I believe .38" is the nominal diameter of a loaded round of .38 Special, measured outside the cartridge case, not the diameter of the bullet (which is .357). I think there is some weird historical chain of events related to earlier cap and ball revolvers as to why that non-standard way of designating .38 Special came about. Quote Link to comment Share on other sites More sharing options...
spandit Posted November 4, 2013 Report Share Posted November 4, 2013 Shotgun calibres are measured by the size of a sphere you make from a pound of lead. For example, if you divide the pound into 12 and make each portion into balls, each ball is 12 bore, likewise for 20 bore (but not .410) I notice 243 is 3^5, not sure if that's why they went for such a seemingly random diameter Quote Link to comment Share on other sites More sharing options...
Floating Chamber Posted November 4, 2013 Report Share Posted November 4, 2013 (edited) Shotgun calibres are measured by the size of a sphere you make from a pound of lead. For example, if you divide the pound into 12 and make each portion into balls, each ball is 12 bore, likewise for 20 bore (but not .410) I notice 243 is 3^5, not sure if that's why they went for such a seemingly random diameter 12 gauge. Gauged from a ball 12 to the 16 ounces. Wrongly called '12 bore'. (even 'tho I often use the term.) .410" is a bore.* * so will I be, if I keep putting folk right! Edited November 4, 2013 by Floating Chamber Quote Link to comment Share on other sites More sharing options...
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