Does anyone know if there is anywhere in Korat that supplies these?

I've never visited following location (added to my todo list), so ask (phone):

http://www.thongsomboon-club.com/

not implying that they're actually using them. One of their website pages coins the term B.B. Gun.

And, as a very special additional not unimportant date related gift, enjoy looking at a much more modern maa below:

Mai <whatever> but Roald Dahl (1916 -1934).

Naam pai poen ? I am.

Pai !!! ; - )

Thanks for the reply jacni2000 I will contact them.

Sorry but I don't understand the 2nd part of your post

Pah!

These look like the standard 12g Co2 cartridges used for pellet pistols etc. No doubt the genuine Umarex item is very good, but do you really need to be that fussy? You can buy the standard cartridges in many places - got my last lot from eBay, though not in Thailand. I have even seen people use the shorter sparklets soda syphon cartridge at a pinch with a spacer cut from an old one. Apart from use in paint balling and airguns, cartridges like this are also used (with an adaptor) by competition cyclists for rapid inflation of tyres.

To not exclude advice of field experts I decided simply not to go bitly on this one.