the 6.5mm "jaybird" ... a new cartridge that does nothing not already done ... be happy to sell you some ...

friends:

if i "just had to have" a 6.5mm cartridge for the ar-15 platform, ... , "all the rage", ... , don't you know, this is how i would go about designing it.

i would run a 6.8mm remington spc up into a 6.5x55mm swede sizing die, and size the neck to 6.5mm.  no other alterations to the case.  then i would take a 120 grain 6.5mm bullet, seat it to an overall cartridge length of 2.255", using a 6.5x55mm seating die, and be done with the whole thing.  i would send the completed round off to huntington/rcbs for the construction of dies, and then i would be done.

i would work up the same loads i use in my 6.8mm remington spc, only decreasing the charge weights accordingly, because you cannot push a 6.5mm bullet down a bore without encountering more resistance than with a .277 bullet, due to the bullet's inertia and increased bearing surface.  

reduce the caliber per bullet weight, live with a little less velocity.

fact of life.

but, the bullet will fly better with a somewhat better trajectory.  it would be a matter of empirical research to find out whether the new creation had any practical advantage to the 6.8mm out to any practical range.  (hint: you could cover the performance/trajectory/delivered energy differences between a bullet of .264" diameter and a bullet of .277" diameter in a 120 grain bullet out of the same case with a hot dog wrapper.  trust me.  i've looked into it.)

but, i will be the proud owner of a 6.5mm "jaybird."

and, i would be more than happy to sell you the dies or loaded ammunition, or complete ar-15 rifles, if you would like.

update:  could not do it.  the 6.5x55mm sizing die is just too big, too long, the little 6.8mm case just couldn't reach the neck sizing portion of the die.  so, then it struck me.  why not use a 6.5mm carcano case to fabricate my new cartridge.

and, then it just struck me, again.

if you must have a 6.5mm cartridge for your ar-15, why not just chamber one for the 6.5mm japanese service round, used in the type 38 arisaka rifle?  you could call it the 6.5x50mm arisaka, and no one would know that you were using a round deemed obsolete in the 1940's.

and, you would have your 6.5mm cartridge, "all the rage," you know.  a much better case design than the 7.62x39mm russian the 6.5mm grendel is based upon, a little larger at the base of the case, and a better shoulder for feeding in an auto.  and, just about the same ballistics.

isn't it wonderful to be on the cutting edge of technological development?  laughing.  end update. 

john jay @ 12.10.2010

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