I use armslist, even for non-FTF deals. While admittedly a little risky I've never run into problems by using a little common sense.
1. Is the price way too cheap on a very 'high status' firearm? If it's a SCAR 17 for $2200, an HK MR762 for $2500, etc, that's a big red flag.
2. Is the location listed as 'State, State'? For whatever reason, 90% of scams list the state twice rather than city, state. Big red flag.
3. Do a reverse google image search, often times you'll find the exact picture in use somewhere else. Big red flag.
4. Do their emails sound funny or vague? I like to discuss specifics of the firearm, this also weeds out most scammers that just copy/pasted description.
5. Lastly, can you get them on the phone?
Using the above, I've done tons of non-FTF deals with expensive items, and am currently batting a thousand. I've also weeded through TONS of scams, so YMMV.