I use RL15 in my 505. With 105 grs for the 600 Hawk and 110 grs for the 525 Woodleigh and 535 Hawk. These are moderate in mine, but should be worked up to in any other 505. There is a web page available with a lot of 505 data that can be found with a search using 505 Gibbs. Also, kapok is used to contain powder charge in bottom of case.

4350 seems a mite on the slow burning rate side, but maybe ok.

Bertram brass is so soft, it is difficult to tell pressure by head expansion. Hornerber is good, and that is what I use now.