i beleive you can reach the velocity safely magman.when i got my 257 barrel i contacted sierras tech service,they said for every inch of barrel you loose you loose app. 40-60 fps.(they measure this with a standard 22"length barrel.)they also said at handgun velocities the "varmit"weight bullets will serve dual purpose as a "deer bullet"i have had great sucess with the 90 gr.hpbt gameking.i also loaded some of the 85 gr. nosler silver ballistic tips to try out,they are real close to the sierras in the accuracy dept.i figure the 257 jdj kills all kinds of deer size game with the light weight bullets,my 257 is so close that a deer will never know the difference.with my .257 caliber guns(both pistol and riffle )i have always had good luck with imr-3031 powder.as for the scope...i have no ideal,but let us know because im thinking i need a little more "glass"on my 257...good luck.jim257