Chaser,
I'm farily new in this gun thing (actually laid dormant for about 3 decades - but that's a another story) - anyway, I have bought a few guns by mail, and have not gotten burned yet.
However...besides feedback, as one reader suggested. I think the safest way is to use visa/MC or, a check that is tied to a Visa/MC account. On two occaisions, even though the seller wanted only certified/money order, I explained that I have an account that is tied to a credit line - guaranteed funds. On both occaisions, the dealer said "fine - just need to wait for the check to hit your bank". In my case it really is a credit line, but in other cases paper checks can usually be obtained that tie to a Visa/MC account. In either case, if the goods do not come thru, you contact the your Visa card co. or bank, and they do a dispute resolution.
Hope that helps.
- w