Call Warren Jensen at lost river bullets ballistics http://www.lostriverballistic.com/ . If anyone knows...he does. The company also work up handloads for a fee for customers with their bullets....so they will know!

I know that a .264 Winchester has a tough time doing any more than about 3600 to 3700 fps with a 100 grainer, and this is with a bit larger bore to work with. Since these cartridges have long since reached the point of diminishing returns with case capacity, I would sincerly doubt reaching 4100 fps with a .257 STW (at "sustainable" pressures and with a barrel of any practical length).

Just ran loadtech. Even with 32-34" barrels it is basically impossible to reach 4100 with a 100 gr.

I read an article about a custom built rife {.257 stw] shooting a 100 grain J-36 bullet,[powder] was reloader 25.. measurment unkowon, At 4100fps.With 3/8" group @ 100 yards.Bullet drop= +1.89" @ 100 yards +3.15" @ 200 yards +1.78" @ 300 yards dead on @ 350 yards -2.58" @ 400 yards -10.27" @ 500 yards... I am needing help with powder charge for this load..This load @ 4100fps has safe pressures.ANYONE that can help me with powder charge or reloads .257 stw please reply..

I checked Quick load but it doesn't have the .257 stw. Hopefully someone with some experience will chime in here but 4100 out of a 100 grainer sounds awful amibitious unless this gun has one heck of a tight chamber and long barrrel. I can get almost 3700 out of a 100 grainer (pushing it hard) in my .257 wby with 26" barrel and I think this gun is pretty "fast". For that stw to pick up another 400+ fps out of 10 grains more powder just doesn't seem possible unless there are some "special"things going on. Just my opinion and will gladly watch here for more info.