The 6 Dasher(or 6BRX) has set more records at 600 and 1000 yards than any other round. For IBS, it's the only round to shoot, IMO. It's deadly accurate, light recoil not upsetting you bags, and efficent to load and shot. Also, a quick look at Quickloads shows this: a Berger 105VLD running at 3050fps(easy for the Dasher) has 34.9" of wind drift at 1000 yards in a 5mph wind. A Berger 180VLD running at 2850(running a straight 284 - hard) has 29.7" of drift in the same wind. 5" of differences between the two...Is it that big of a difference??? Shooting F-Class, maybe...Shooting IBS, not really as you are shooting for group or score, as you can't win both from the same target..
BTW, a note on the Dasher....I shot a Dasher to 16th overall at the 09 F-Class nationals..There were alot of big cal's under me when it was all over, and Butner winds are tough. I sent hunderds of dollars, lots of time switching over to the 284 Shehane, then too the straight 284...The Shehane give me hell with vertical...Finished 15th at this years F-Class nationals shooting the 284 Shehane....I wonder how I'd finished if I'd been shooting my Dasher that never has vertical problems? It's all what your comfortable shooting, but mainly, about have 100% confidence in what you are shooting
I'm back to running my Dasher now, and will be doing so until I have to screw the 7mm back on for the F-Class team shoots and tryouts...
Good luck..