the demise of the norma magnum case can be summed up as a marketing failure on norma's part. although rifles were available in this caliber, only brass for reloading was available in large quantities, with norma the only manufacturer of ready made ammo. winchester, however, was able to produce the popular model 70 rifles in their caliber and mass-produced ready made ammo to the american public. this was the main reason of the 300 winchester magnum's popularity over the 308 norma mag. the 308 norma magnum is considered by many reloaders as a better caliber compared to the 300 winchester magnum that essentially replaced it.