bulldog:

Welcome to the Party.

A couple of suggestions. This site is great for DR questions. Many of the same people on here also post on www.accuratereloading.com. Do a search on both sites for anything and everything you can think of about DRs.

Second, I see you said you are going to SCI in Reno. Great idea! Most, if not all, of the big DR builders will be there. It's the best single place to go and shoulder the various makes, models and calibers of DR. Find the one that fits you best. Also, Dallas Safari Club, a week after SCI, is another good place to go. It's not as large as SCI, but many of the same faces. I'm going to DSC and getting together with a bunch of guys who post on AR.

If you are in California, I would highly recommend giving Butch Searcy a call and taking a road trip to visit his shop. Butch is one stand up guy and will give you the grand tour of the place. Searcy makes one hell of a DR.
(He's planning on moving his base of operation to SD, but not sure what his time frame is.)

.500 v. .577? The .500 is probably a better caliber to start with - I have a .500 and love it, and my Pop is getting a .577 from Butch.