There is no ammo 5.6x50R available but I have been able to get brass, RWS and S&B off the internet, single shot break actions don't go through a lot of brass. Dies were off the shelf from Hornady and C&H carries them also. Hornady has load data.
I had a combo gun in 222 Rem/12ga and seriously looked into 222 Rimmed but the only factory brass was Bertram and I've had poor luck with their stuff in my 6.5x58R Sauer. Brass can be made from 357 Max but it is a lot of work.
I only ever neck size, so when I got my 5.6x50R I simply used the .222 dies I already had on hand, and they work fine.
I used Bertram's brass in my .222 Rimmed. I'd have to concede that it didn't seem quite up there with premium brands like RWS. I think that if I was to have a .222 Rimmed again I'd use RWS brass, sized and trimmed. It is admittedly pricey, and the initial preparation would involve some work, but once you'd made 50 or 100 pieces you'd be set for a long time as long as you didn't make a habit of losing cases, didn't load them up to the ragged edge and annealed the necks every now and then.
