Originally Posted by 65WSM
First we need to know the length of the Berger 170 gr bullets to use a formula to figure out the stability of the bullet. The Greenhill formula is the best known but RSI says they have a nore accurate one.
Second, what kind of powder are you using and what charge. It sounds like you have a real impressive load. Remember that 140 Accubonds have a higher BC than the Bergers.
For 170gr bullets I would expect that VV N-570 would be your highest velocity powder.
Bob Beck says on this thread that the 170 grain Bergers will be 1.52 inches long. The temperature will be around 50 or more degrees, the height above sea level say 500 ft to 2000 ft.
I'm using 73 grains of H4831sc in the 270 Dakota behind 140 Accubond for 3,420 fps with 27 1/2 inch barrel and 67 grains H4831sc in 270 WSM behind 130 Accubond for 3,260 fps with 25 inch barrel.
As I use 1 in 10 twist barrels, I need to determine how fast the .277 170s need to go to stabilize, to work out if I can use them. I haven't used stability formulas before and not sure how reliable they are.