The family should do pretty well financially on this auction. There are tons of people out there who will bid on anything that Al owned,so they can tell their friends "this dresser was once owned by Al Capone".
As far as the .45,I think that it will be the runaway star of the auction. They're starting the bidding at 100-150 K,but I'll bet that it brings in 3 or 4 times that. This assumes, of course, that they can provide sufficient provenance for the item. To be honest,if I had an extra 150 K under my mattress,I'd bid on it in a heartbeat.