I know that Glock says not to use lead in their barrels but I also know that many do it anyway. When I have questioned them as to what effects the Lead has had on their barrels they say none - but it does need to be cleaned thoroughly afterwards. I also know at least two shooters who have bought special replacement barrels for Glocks that are "OK" for Lead bullets.

In any case, I'd start at the lowest recommended charge (from the Powder Co's loading charts) and adjust from there. I used Lead re-loads for about 5 years when I use to own a Browning Hi-Power but don't have any 9's anymore, - got heavily involved in .45 acp's instead.