I couldn't find this reported anywhere, sorry if this is a known bug.

If you change the bullet type of guns like Spas or M79 (don't use bullet type 1) to have bullet type 1, the bullet does not appear.

I think that 'bullet.bmp' should be the graphic used for weapons using bullet type 1. However, 'bullet.bmp' is used by the stationary gun, so maybe a 'm2-bullet.bmp' graphic would be handy (to make modmaking easier).

Yes you are right. I can fix it but not fully. The modded weapons will have to use bullet.bmp.

mmh then let the statgun use its bmp with a different name, so the bullet.bmp is free as "default" bullet and statguns wont look weird when shooting :p