Re: 338 LM Improved w/ gain twist barrel
I shot 8 more of the 276s again today, to verify velocities so I can add more info to the mix from yesterday's range session. Today it was nearly identical as yesterday for weather. I shot my last 295 6.5 Caliber as teh 100 yard zero calibrator and get the ball rolling. I then shot 8 of teh 276s, watiing 2-3 minutes between shots.
The load was not a developed one, but simply one that I know was going to be safe (it was 2.0 grains less then what had popped/leaked on my yesterday). Anyway, the load produced an average velocity of 3,106 fps an ES of 30, and was a 1.0 minute load. Given that teh minute was mostly verticle, I suspect a real accurate load is nearby, but not the 103 grains of Retumbo that I was using. I also think that today's velocities confirms my estimate yesterday of 3,150 to 3,200 fps for the top tested velocity.
FYI until I can do more at distance elevation and drop testing with known loads and color coded bullets, I'm calling the ball on BC on the ZA 6.5 at 3,200 fps as roughly .940. That does not suck too bad at all... But since that speed is not one thatI can or want to replicate it is likely of interst only to the 338/408 shooters where I believe 3,300 - 3,400 fps is easily within reach.
Noel wanted me to also mention that given my recent success with the 6.5 caliber ZAs, he wants me/us the start testing the 7.0 caliber projectiles as soon as he can get some produced.
When I get them and shoot them, I'll let you know what they do.