To be honest, the seller needs as much scrutiny as the rif itself, easily done when shopping on forums.
Look at how long a member, kind of feedback, post count & maybe have a look at the quality of his posts, if he's spamming/poor attitude/thick as shit, I'd be reluctant to consider buying something with complicated moving parts etc.
Also, regarding the rifs, if the seller is the first owner - IT'S SECOND HAND
if its like new- IT'S SECOND HAND
if it's only been skirmished once - IT'S SECOND HAND
Don't get sucked in to any of the bs, once a rif leaves a shop for the first time it's second hand, open to abuse or excessive use, or just natural wear & tear that will at some point lead to failure.
& again, irrespective of alleged god like condition proclaimed by sellers, NO WARRANTIES APPLICABLE, no matter how much your paying over the odds, YEAH I'M LOOKING AT YOU @avenger63😜.
As for what to actually buy, find what you like the look of, look to see if it's been reviewed on here, if not make a thread asking about it, in no time at all you'll be inundated with responses👍