Other manufacturers do make ammo but its the caliber that makes things difficult. Most make the 300 WBY but not many make the 340 or 7 mm. Something to keep in mind if your buying a weatherby. You can save a few bucks if you already handload, I don't and the ammo up here is almost $50 US. What I don't understand and it may be pure marketing, is the ballistics for Weatherby/Norma manufactured ammo is better than ammo manufactured by companies like Federal or Remington. Your best bet for ammo is Federal. I believe they make 340 Wby also.

Goodluck,