You have your numbers severely scrambled. What you saw was probably 4198 and although they are technically close in speed, I do not see it in common use for 6PPCs. Can you come up with some H322, or Benchmark, or xterminator, IMR 8208, 2015 or LT32? I have worked up good loads with all of them. The LT32 is the newest go to powder and should be available if you look around. On the other hand, if you are happy with 3,350, 2015 is a slower version of the same powder that will do very well. I usually start a new shooter out with Berger 68s marks on the bullet half as long as wide, combined with 322, and have them test from 27 grains up to a tight bolt, in .3 steps, over flags, on an easy wind day. I do not bother with five shot groups until I have something that looks promising with three, and do my .3 gr. step investigation with two, shot rapidly to help insure the same condition. Most primers can work, but I usually avoid 7 1/2s because they seem to me to be too hot.