Cool cartridge that never really caught on. It and the 6.5 Rem Mag were introduced in the Rem 600 and 660 rifles in the 60s. They had very short barrels that did not help recoil or muzzle blast, and hurt ballistics. They are not much different from today's Win short mags, or Rem's SAUM, except that the 350 and 6.5 Rem mags have a belt, while the newer stuff does not. I have often thought about having a gun rebarreled to those rounds, with a 22 or 24 inch barrel, it would give good ballistics. Performance wise, the 350 Rem Mag is very close to a 35 Whelen, except it can fit in a shorter action. I know Ruger made a few of those not long ago in their Ruger 77.