- May 1, 2012
- Denver area (Lakewood, CO)
So am I to read from what you wrote that this 277 Sig case is exactly the same dimensions as a 6.5 needmore? It is not. Or did you mean you necked it down to a 6.5 Fury and then rechamber a donor needmore to fit the 51mm case? Needmore is a cartridge, not a caliber just the same as a .264WM and a 6.5PRC are cartridges, not calibers. So unless you somehow found some .277x 48s or you were able to squeeze a steel, brass and aluminum case body down from 51mm to 48mm, then you didn't neck it down to a 6.5, you necked a 277 Fury down to a 6.5 Fury. Please clue me in if I am wrong with this assertion.The 277 bi-metal case is rated at 80,000 psi.
Couldn't get a 277 fury. So I used the case necked down to 6.5 Creedmoor, with a donor rifle to sacrifice. Been checking for lug set back, and barrel wear. But this case really improves the velocities of the 6.5 Creedmoor and 308. A dangerous endeavor, and do not do it, according to the manufacturers, the bi-metal cases are not to reloaded. But I did for this experiment. The 6.5 ,Creedmoor will run 150 SMK at 3050 fps...backed off to 3000 fps and ran a bunch...reloaded them 3 times, so far no lose primer pockets no case head swipes. Fireformed a bunch more today with 140 gr averaged around 3124 fps for all 15 rds. 147 eldm were runing 3039 average fps on fireforming. Much faster than the brass cases 6.5 Creedmoor at 2600 fps...to maybe 2800 with the right powders. In the same barrel. Bi- metal cases at high pressure add performance...but at what cost. This is my personal experiment, not recommended by any manufacturer. But I hope they the bugs worked out of the accidental discharge, trigger problem, and longer barrels available. Although a 16" light 277 hunting rifle would be a nice back country hunting tool.