Is 7TCU ammo available commercially or is it a handloading the only option ? I don't reload at least yet .....
It is a reloading proposition. There might be some small specialty shop that makes/will make it but prices are likely to be high and options very limited.
Check to see if there is a IHMSA Silhouette club near you. I know that their numbers are dwindling, but give it a try. The 7TCU was very popular with silhouette shooters and you may find a club member who would let you reload some ammo using his equipment OR may be willing to load some ammo for you.
Reed's Ammunition on the Internet. They used to sell it.
That's a great little cartridge. Lot's of power to be so small. Not hard to make either. But you can't buy it at Wally World. I would get a 7-30 Waters if I wanted it in a Contender. That ammo. is not real easy to find.