July 27, 2014, 06:55 AM | #26 |
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Jim, those .307" groove diameter barrels were first made for arsenal 3075" diameter 7.62 NATO bullets. Probably in Great Britian or one of its Commomwealth countries. They aren't allowed to use handloads and every one has to use the same lot of ammo. Their arsenal ammo bullets are sometimes .3070" diameter so they use .3065" groove diameter barrels to shoot them accurately. They often to all that very well.
In 1991, when Sierra first made their Palma bullets, they were .3084" diameter. They shot 1/2 MOA at 600 in .3065" to .3080" groove diameter barrels. All their previous HPMK 30 caliber ones were kept at their same size of .3082". I have no idea why that diameter was used. Last edited by Bart B.; July 27, 2014 at 07:05 AM. |
July 28, 2014, 09:39 AM | #27 |
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Add to the confusion that some wildcats are described in their early days by simply naming the bullet size and case. Such as the .30/5.56 - the slash designating the combination of the two components.
If it has any chance of success then the inventor will rename it, buy using the bullet diameter number that will embrace a distinction, then, adding their name. If then introduced by a major Brand, they get "naming rights" and add their own. And often as not, the inventor decides to embellish even further with an obscure reference to mythology. Or, dissimulate any connection at all, to cover it's origins. The result is the 6.8SPC Remington, or the 6.5 Grendel. Now, if another maker decides to copy it and contest the market by challenging shooters to adopt a name by popularity, we get the .264LBC. And AAC renames the .300 Whisper and it becomes .300 Blackout. Improve the chamber and make ammo that will only shoot in those guns safely (which is arguable,) and you get the 6.8 SPC II, or all the "Ackley Improved" versions. Add some trying to embellish the round with their aspirations of it becoming official - and therefore being able to buy cheap surplus - and you get 6.8x43 NATO. There are barrels so marked on the market. So, you wind up with a cartridge loaded with a .277 bullet, in the .30 Remington (Rimless) case, and yet to be issued by any NATO signatory. The real purpose of a cartridge name is either to officially designate it in the inventory of a military establishment, or to market it to the general public. And there are few rules that ensure any dimensional accuracy other than to be specific about what it constitutes. The naming is more based on it being the least likely to be confused with it's nearest in size, and sometimes the system doesn't work. 9MM Kurz isn't 9mm Luger isn't 9mm Parabellum, but you have to know it for sure rather than guess. On the other hand, the various .22's, from cap to Long Rifle, are nearly interchangeable in some guns, although the results are dramatically different. Goes to some shooting enthusiasts who collect cartridges, and the trade in exotics or rare ones amounts to a significant portion of our hobby. |
July 28, 2014, 01:32 PM | #28 | |
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Quote:
Example. .25-06. |
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July 28, 2014, 11:08 PM | #29 |
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And be careful if you shop British.
A .450-.400 is a .40 caliber; they give the parent case first, then the neckdown. |
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