RimfireCentral.com Forums - View Single Post - .260 REM vs .260AI vs 6.5 REM Mag vs 6.5x284 Norma
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Old 06-19-2009, 02:09 PM
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aom22
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6.5x284 As Suggested by natman

Quote:
Originally Posted by natman View Post
If you feel compelled to make a change consider the semi-wildcat 6.5x284. No bolt head change needed.
Quote:
Originally Posted by natman View Post
"Here are the case capacities of our two cartridges.
  • 6.5mm-284 Norma = 68.33 grains of water
  • 6.5mm Rem. Mag. = 68.64 grains of water"
So I don't see how the 6.5-284 can be "over-kill" since its capacity is slightly less than the 6.5 RM.
natman ... I've been doing some research on the 6.5-284 cartridge.

I've looked very closely at the ballistics of some of the off-the-shelf loads available and I'm dumbfounded.
You were (are) right ... the 6.5x284 will perform, almost precisely, at the level I'm seeking.
Quote:
Bullet: 160 grain Sierra Spitzer Flat Base Pro-Hunter
Velocity: 2650 feet per second
Ballistic Coefficient:0.37
Required Twist:1:9 inches or faster
Use: Deer. Elk
Bullet Construction: Gliding Metal Jacket. Lead Core

Bullet: 140 grain Sierra Boat Tail Hollow Pont MatchKing
Velocity: 2760 feet per second
Ballistic Coefficient:0.53 Required
Twist:1:9 inches or faster
Use: Long Range Match
Bullet Construction: Gliding Metal Jacket. Lead Core

Bullet: 142 grain Sierra Boat Tail Hollow Pont MatchKing
Velocity: 2760 feet per second
Ballistic Coefficient:0.58
Required Twist:1:9 inches or faster
Use: Long Range Match
Bullet Construction: Gliding Metal Jacket. Lead Core
A few more elementary questions.
Is the 6.5x284 the same as the 6.5-284 Norma

Wildcatting the .284 Winchester
Quote:
The single complaint against the .284 is the rebated rim.
In some types of rifles, this can cause a bit of difficulty for the gunsmith.
It makes proper magazine lip configuration a bit more critical--poorly designed feed lips
can result in the bolt overriding the next round, rather than picking it up.
While a real consideration, it is the trade-off for allowing use of a 0.50-inch-diameter case
with the conventional 0.47-inch-diameter bolt face.
Moreover, this is not a serious problem when the gunsmith knows what he is doing.
What length action is needed for a rifle to function as a repeater with this round.
Considering the odd combination of short case length with long overall length.
What caliber detachable magazine will this case feed out of.

The Long-Suffering 6.5
Quote:
However, if you put a 6.5-.284 Norma, 6.5mm Remington Magnum or even a .260 Remington cartridge
into a .308-length action you do have concerns about bullets of 140 grains
and over intruding into the powder space.
And that's another reason we haven't seen, and probably will not see, a factory 6.5mm short magnum.
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