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ARE “These 6.5 MMs are hot?”
Under the heading, 6.5-.284 Winchester, on page 28 Lane Pearce, in Oct. 2016 Shooting times states “There is also a domesticated version called the 6.5-.284 Norma, which has the exact same case dimensions as the original wildcat.” [Emphasis is mine.]
This is not true. They are different chamberings because all of the cases for the 6.5-.284 Norma are larger, requiring a different reamer.
Lapua cases are .499 at head, .471 at the shoulder.
Norma cases are .498 at head, .474 at the shoulder.
Nosler cases are .4975 at head, .474 at the shoulder.
Hornady cases are .4977 at the head, .4725 at the shoulder.
Winchester cases are .494 at the head, .469 at the shoulder.
Cases are too large in the Win. chamber as the reamer measures .499 at the same distance measured from the shoulder to extractor groove at the head. The shoulder is .475 as the 6.5-.284 cases. Reamers of 6.5-.284 Win. are made specifically for Win. cases.
Reamers for 6.5-.284 Norma are made specifically for Lapua, Norma, Nosler, and Hornady cases. Norma reamer is .5005.
Overly tight situations are encountered with all of the cases of 6.5-.284 manufacturers in a 6.5-.284 Win. chamber. And the cases must be loaded to a much lower pressure level than the Win. cases. Win. 62000 PSI, all others 54000 PSI or they stick in the chamber.
The Win. version is capable of 200 fps. higher velocities than the Norma version because of cases and chamberings. Pressure spikes come quick using the wrong cases in the wrong chambers that are dimensionally incompatible.
It is necessary to use a 1” micrometer that reads 1 ten-thousands of an inch and learn how to use it. In other words, know your subject material to avoid getting folks into trouble by attempting the wrong loading practices.
We once had the knowledge base in a couple of writers, but they are gone. And it seems as though there is no one writing to replace them.
8-15-2016 © Randy’s Custom Rifles
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