I can't answer your question, but I will address the issue of a replacement ban.
1. GWB may be in favor of a ban, but he is only the guy who signs the bill, not the one who passes it. Thats up to the House and the Senate.
2. Count on it being an election issue, and unless we get real lucky, it would probably pass in the house.
3. The key will be the Senate. Representatives are up for election every 2 years so it will be an election year for all of them. But, Senators only run every 6 years so only about 1/3 will be up for election that year. They will probably vote for the ban unless they are pro-gun on the record and figure to win anyway. The key votes will be those Senators who aren't up for election. They are the ones we have to reach and convince that if they vote for the ban, we'll remember and vote them out when their turn comes up.
We don't have to win every battle here, just one. If we can keep the Senate from passing the ban, it doesn't matter if GWB wants to pass it or the House passes it. It stops at the Senate.
I'm not a politician, nor do I play one on TV. If someone out there knows more about the system, please educate me, but thats my analysis.