I just noticed this cartridge on ammoguide.com . It's called the .10 Eichelberger Dart.

http://www.ammoguide.com/cgi-bin/ai.cgi?sn=LAJOhstsuv&catid=318

Has anyone heard of a smaller calibre? The 2.7mm Kolibri works out to about .106 cal.

Http://www.lakesideguns.com/

This site has many micro calibers for things like keychain derringers and whatnot. I remember reviewing firearms with calibers smaller than .10 . Just read around there is no limit to what people can come up with.

Oh yeah,

I remember now, there was some 2mm pistols and stuff, I think they even get smaller than that! Oh, also try http://pinfire.homestead.com/Austria3.html
The smallest I know is of the Belgian 1mm Muff Pistols.

Neat stuff. Thanks for the links

I think even my wife would agree that these rounds are just plain "cute".

Here are some of the kids beside their parents...
http://ammoguide.com/gfx/web/tens-2.gif (http://ammoguide.com/)

.10 caliber is about the smallest you will find with rifled barrels. They are not for miniature guns, but full size guns (usually chambered in the parent cartridge of the small round) that have been rebarreled to take the smaller round. Bolt modifications are not necessary, because the rim of the parent round is used unmodified.

Miniature guns that shoot cartridges like the 2.7mm Kolibri are smoothbore.

Mike Haas
http://ammoguide.com/

Dixie Gun Works used to have 2mm pinfire ammo for miniature guns that used to be popular in Europe. Might still have it.

Also - there is a round called .22 flea, which is a .32 acp necked down to .22, supposed to be about like a .22 WMR ballistically. RCBS has dies, supposedly a fairly popular wildcat.