Re: 6.5 RUM
I have two 6.5mm magnums in the herd. As mentioned the 6.5mm AX is based on the 300 Dakota case, necked down, shoulder sharpened, not quite to 40 degree angle and body taper reduced. This round will get you 3750 fps with a 100 gr pill, 3500 fps with a 120 gr and 3300 fps with a 140 gr class bullet all in a 26" barrel length.
My other round is the 6.5mm Allen Magnum which is a 338 RUM necked down, sharpened shoulder angle and body taper reduced. The capacity of my 6.5mm AM is actually a couple grains larger then the standard 6.5mm RUM based on the longer 7mm RUM case.
Performance numbers are 4100 fps with a 100 gr pill, +3800 fps with a 120 gr, +3550 fps with a 140 gr pill and 3300 fps with a 160 class bullet all in a 30" pipe.
Any round with this size of case capacity and this small of a bore diameter can be seriously effected by powder bridging. For this reason I recommend only ball powders be used in my two rounds.
As mentioned barrel life will be limited which is also why I recommend my chamberings only for big game hunting rifles where high volume shooting is not common or at least should not be common!!! [img]/ubbthreads/images/graemlins/grin.gif[/img]
For that purpose, useful barrel life will be for many, many seasons!! For some shooters a lifetime.
I would like to say that if you get into a round of this extreme range, be prepared for some issues that will need to be delt with. There is a cost for extreme performance and being an exprienced handloader is a must and paying very close attention to what is happening with load development is also a MUST.
Things can go from normal to dangerous very fast as you climb the performance scale. They work great if you pay attention but will bite you if you do not!!
Allen Precision Shooting
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