will 4 rifle scopes pass the customs?

Why the repeat post? Its not like you asked days, weeks months ago.

As usual Westwood got in before me

Ah but my day starts before yours.

The notice at BKK actually says "Passengers who would like to load firearms with the aircraft, please contact airline staffs at check in counter"

The sign is just at the entrance to international departures just before immigration.

You are only taking scopes. If you can load firearms then I doubt scopes will be a problem.

will they open my bag after x-ray??

Dunno if this is a good idea.

There was a dude who got arrested for carrying a bullet proof west:
http://www.straitstimes.com/asia/se-asia/british-journalist-arrested-at-bangkok-airport-over-bullet-proof-vest-plates-gas-mask

IIRC there was a similar case at Hongkong airport (or was it Japan?) at one point.

Maybe check with the airlines, too?

This is interesting; it says that (empty) anmo clips being parts of weapons are under same restrictions as weapons.
They do mention scopes there, too.

Documentation required.
(Probably an export licence from some gov department).

Link:
http://www.jusmagthai.com/sensitive

Dunno if this is a good idea.

There was a dude who got arrested for carrying a bullet proof west:
http://www.straitstimes.com/asia/se-asia/british-journalist-arrested-at-bangkok-airport-over-bullet-proof-vest-plates-gas-mask

IIRC there was a similar case at Hongkong airport (or was it Japan?) at one point.

Maybe check with the airlines, too?

I see. Sloppy journo.

airline is AirAsia