I heard of this at a different forum but can't find any info on it. They said it is based off the STW with a 35 degree shoulder but that is all that was said. Would like some more info on this if anyone knows.
Too close is knife work, ie barrel thumps em on the head [img]/ubbthreads/images/graemlins/smile.gif[/img]
Just think of it as a 6.5 Win mag with a 150fps increase in velocity. The 6.5STW is a way overbore cartridge but if ultimate performance in a 6.5 is desired, it will do it. Certainly something to consider if using new gen heavies and long barrels.
The 6.5 STW and 6.5 Thor are great rounds but will not get the 3500 fps you are looking for with a 150 gr bullet. In fact I would dare say that this is not really a pracitical velocity goal in a 30" barrel in the 6.5mm bore diameter.
My 6.5 Allen Mag is based on a necked down 338 RUM with the shoulder angle increased and body taper removed and It will push this velocity with a 150 class bullet in a 30" barrel.
I have also tested my 6.5mm Allen Xpress which is a 300 Dakota necked down to 6.5mm with the same AM shoulder and body configuration. This round will actually match or slightly beat the STW in velocity potential and in a shorter 2.550" case length. With a 140 gr bullet you can get 3320 fps in a 27" barrel, close to 3400 in a 30" pipe. This is basically what the 6.5mm STW and Thor will also get.
I have only tested the 6.5mm AM a limited amount but have tested my 257 AM extensively which is identical to the 6.5 AM only with a 257 bullet. This round will will drive the 156 gr ULD RBBT Wildcat Bullets to just shy of 3400 fps so it gives some idea what the 6.5mm version would do.
Unfortuntely, these two rounds, with their sharp shoulders and near 100 gr case capacity are only usible with very slow burning ball powders such as AA8700 and the new US869.
In the full length STW case though, I think you will be limited to 3350 with a 150 gr class bullet at safe pressures.
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