For hot loads in 357 Redhawk, I agree with you, six shot is the way to go.
Regarding H&G #321, 200 grains, i tried to scale drawing and seems to me that distance from crimp groove to tip is about .470". Combined with 357 Magnum case, this will make round with 1.760" OAL. If 357 Magnum Redhawk has a long cylinder like 44 Magnum or 45 Colt, it could take round 1.790" OAL (plase correct me if I am wrong). In that case, 360 DW load data might be used https://www.danwessonforum.com/forum/reloading/loading-data-from-the-old-dan-wesson-website/ .
As for loads used in FA 353 http://www.sixguns.com/tests/tt353.htm , I wouldn't use them in 357 Redhawk. Redhawk is six shot and bolt notches are close to chambers. FA 353 is five shot and considerably stronger gun because bolt notches are between chambers.
Regarding H&G #321, 200 grains, i tried to scale drawing and seems to me that distance from crimp groove to tip is about .470". Combined with 357 Magnum case, this will make round with 1.760" OAL. If 357 Magnum Redhawk has a long cylinder like 44 Magnum or 45 Colt, it could take round 1.790" OAL (plase correct me if I am wrong). In that case, 360 DW load data might be used https://www.danwessonforum.com/forum/reloading/loading-data-from-the-old-dan-wesson-website/ .
As for loads used in FA 353 http://www.sixguns.com/tests/tt353.htm , I wouldn't use them in 357 Redhawk. Redhawk is six shot and bolt notches are close to chambers. FA 353 is five shot and considerably stronger gun because bolt notches are between chambers.
