Yeah, I stocked up and bought 150 rounds of .351 ammo at $75 bucks per 50 rounds (in the 1980's)....then my Dad gave the rifle to my nephew! So I traded the ammo to the kid for my first .22, which his dad (my brother) had persuaded me to part with years earlier.
BTW, Old Western Scrounger sells bullets for the .351 as well as loaded ammo. I believe the bullets are plated cast lead. They are 180 grain, same as all original loads I know of. And if you want brass. contact E#llwood Epps. I know you can use .357 Maximum, but it's a bit of work.