Well guys and gals, as promised, did some testing on or new 150 gr .277 SBD2 bullet using a borrowed rifle 6.8 Western with a 3" short action and Winchester brass derived from a box of factory loads using a 162gr Copper Impact bullet. As the photo shows, my loaded round OAL was 3.000" so that I could have a jump of 0.025". The OAL of the factory load was 2.88". This discrepancy illustrates my point of using 3.2" long actions for these new short fatter magnums to allow mag feeding while capitalizing on the use of high BC bullets. I was able to measure BC on both the new 150 gr SBD2 and the Winchester Copper impact bullet using the Lab Radar. Had to hurry as a winter storm was due to come in soon.
The stats on the SBD2 are as follows:
1) Bullet length: 1.635"
2) Boat tail 0.277"
3) Ogive approx 0.877"
4) G1 BC 0.710
5) G7 BC 0.350
Saw a rather wide velocity node using 57-60 gr of StaBall6.5 with group measuring 0.5-0.6MOA @ 100 yds with final MV at 60 gr SB6.5 of 3080 fps from 24" 1:7 twist Preferred carbon wrapped barrel with Paradigm carbon wrapping courtesy of Matt Kranz who graciously made one of his superb light weight hunting rifles available to me to test with. No pressure signs noted.
Photos show the .277 SBD2 150 gr bullet, and the OAL of the load tested along with the factory 6.8 Western loaded by Winchester using their 162 gr Copper Impact bullet (OAL 2.88"). I was able to also measure the G1 BC of their bullet at 0.566, which agreed with the stated G1BC on the ammo box. I used their brass resized as that was my only source.