Jeff, please pardon me, I didn't really notice this post
I guess I'm going to have to add blind to deaf and dumb.
I have not done enough cast shooting with calibers under 44 to amount to a hill of beans. Practically all my cast shooting has been with 45-70, 45 Colt, 45 ACP and 44 Mag. Along the way I have had a few 357's but I didn't spend enough time with them to be able to say I knew anything about 357's and cast......
That is a little different today. I've actually had a devil of a time getting my 357 Handi to shoot worth a hoot with cast. I have a couple of loads I use and one that Scott17 was using....
I was using 10 grains of 5744 under Lee's 357-158-RF and small pistol primers getting very good accuracy, 10 rounds often in an inch, the norm being 1.25-1.5" Several different loadings of 2400 were promising, but rarely consistantly under 1.5" and usually 2" being the norm. Scott was using 10 grains of Blue Dot, mine wouldn't stay on a 55 gallon drum with that powder, and I assure you I tried every concievable combination. I have yet to be able to use any powder with small rilfe primers and get a decent group. I think the rifle primer generates enough pressure to lift the boolit before ignition and it spoils the ignition/pressure curve. a rifle primer will turn any decent 1.5" group into 3" junk in less time that it takes to register on your ear that the shot has fired. We are of course at this point talking about a 357 Max. I couldn't the original 357 Magnum chambering to stay on a paper plate at 50 yards. After 2 months of struggling, I rechambered it and haven't regretted it for a moment.
The weird part is that i got some of the surplus #107 from gibrass.com. it weighs like almost exactly the same as Blue Dot (comparing fixed rotor chamber weights of the RCBS Lil Dandy Pistol Measure) and shoots a tad slower. (At least in my 44, volume for volume, bullet for bullet) 11.6 grains of this stuff is shooting 1.5" groups at 75 yards and giving me 1500 fps with a plain base boolit (Lyman 358430, a 195 grain RN) that I previously couldn't get to shoot even if I stuck the muzzle to the target. Go figure...............Like DJ suggests, with these NEF barrels of later vintage, slower velocities are going to be the most rewarding for accuracy (under 1200 fps) You will definately need a gas check to push your lead much faster, and full length gas checks don't hurt that situation none a'tall. With the exception of three loads in a years work I have yet to drive a cast boolit from an NEF barrel faster than 1300 fps with predicable accuracy. What they will do under that is phenonemal.
As to the 30-30, mine shows a 6 groove barrel of which the rifling is deeper cut that that on my 357, 44 and even 45-70. I am hoping against hope that this will be a good cast boolit barrel that doesn't require me to work miracles to get decent groups from it. Will know within a few days, and will post to let you know. Sorry I missed this, JPH45