My Sierra book shows 39.2 grs. of AA1680 as max,with it going 1900 fps. If you feel thats not enough you can go up to 33.2 grs. of 296 for 2000 fps.,and if thats not enough you can hustle up a can of discontioned 680 and go on up to 2050 fps.
The 300 gr. load would be 30.7 grs of 296 ( max load ) for 1800 fps. with the old 680 getting you another 50 fps for 1850 fps.The contender will never know what went off in it. :-D :-D Digger