Mine is a GEN one, 350. Legend, Ruger, American. I've been shooting 356 cast bullets in it since day one. 357 won't chamber easily. 35 eights won't chamber at all.
Accuracy and reliability have been very good with 356 bullets.
Jacket I use 355, quantity 165 FTX or 170g Fury, bullets out of Michigan. Dennis fury, makes these bullets specifically for the velocity range of the 350 legend and they are available in 355 and 354 I believe. They perform very well, and they've been very accurate for me if you choose a jacket of bullet, I recommend you give them a look.
I have taken two or three deer with Cass Bullets in that rifle. The first one was a 220 grain MP hollowpoint at about 1400 ft./s. Lungs at about 75 yards and he walked about 35 or 40 and fell on his nose. I shot a small dough with 170 grain ranch dog at about 1600 ft./s. She dropped at the shot.
Ironically, my favorite bullet for the 357 maximum is a 200 grain MP bullet. Originally Tommi boy lent me the mold, and I cast up a big chunk bunch of them. But I have since acquired my own mold. My maximums both of them shoot this bullet very well. I haven't worked out a good load in the legend but it should be just as good as the duplicate 220 grain was.
I also played with subsonics in this rifle and 300 grain Ayres would not stabilize reliably. I didn't push velocity at all. I just shot for speed of sound. But when I drop a 270 grain bullet, I started to get really good accuracy. It's a fun Shooter With just a splash of green dot powder. I like my bolt action 350 a lot better than my AR.
I agree with Tommi boy, 100% when he recommends you steer clear of gunpowder.
1680, 4227, 57,44 have all been good. Loader seven is another one that works OK but doesn't get top velocity because it's so bulky. But 14 or 1500 has worked just fine on our deer here. Good luck with yours. CW.