Originally Posted by overbore
I am old enough to claim a terminal case of CRS--meaning that I have the twist program installed in Excel but do not remember where I got it from--- so with that as given just to be supportive in your excellent bullet project, I ran the 1.721" length, 180gr, MV of 3,100 ( 300wsm ) and .308dia numbers in that program and came up with a twist required of 1-7.5" for SF of 1.30. Dropping the SF to1.25, gives a twist of 1- 7.6". A custom from Kreiger or other first line barrel makers would give your fine bullets a real chance to outshine everything else.Send me a pm if I may assist. Best wishes, Overbore
Thanks for the calculations. We tested the 180s in two different 10" twist weapons and it produced fantastic results. On the 212, it stabailized them as well. However, on the 220 model, we had to use the 8" twist Kreiger to do the testing. The Kreiger and the 220s were absolutely AWSOME.
The most interesting part of all of this testing is that the Wichita Silhouette pistol in .308 with 10" twist barrel shot the 180s into a bughole so small, that you could not put a .338 caliber bullet into it without ripping the target. I cannot explain it, but I am not complaining.
As far as I am concerned, I am very confident on the 220s and the 180s in the twists that we have tested them in. This upcoming week, the 212s will get a lot of attention at different velocities and seating depths to seek out the best combination.......
Preliminary calculations indicate that the 220 loaded to peak performance in the 30/378 (32" Kreiger) will surpass the kinetic energy of both the 265s (.770 BC) and the 280s (.878 BC) (both loaded to peak performance in a 338 Lapua Improved with a Hart 30" barrel) at about 800 yards. Not to mention trajectory and wind drift.
If you guys don't have an .30 8" twist barrel yet, you need to order a good one ASAP.
More to follow later in the week........