Usually TSC gets chicks from one of the big hatcheries. Chances are very high that they will be a Cornish x rock hybrid.It depends on what kind of meat birds they are. The meat birds that ronott1 refers to are the Cornish X Rocks. And, as he stated, they are a heavy bird, and will not do well past their intended "harvest date". However, the Freedom Ranger and the Pioneer meat birds are a slower growing meat bird which reach market weight around 12 weeks. They do well in a free range situation, and can be held over to join the layer flock. I have a Pioneer who charmed me this summer, and she avoided the axe. She's a respectable little layer. In fact, she was the first of my spring chicks to lay an egg. So, unless the employees at TSC are able to tell you exactly what those cute little meaties are, don't buy them, unless you intend to eat them.
Ideal has a Cornish X Rock white broilier, a black broiler and a red broiler. The white is very fast, a 6# bird in 6 weeks. The Black and red broiler are 6#s in 7 weeks. Both of the say:
Red Broilers

Red Broilers are efficient producers of broiler meat for those who do not wish to have white plumage broilers. When broiler rations are fed, producers can expect to have six pound broilers in seven weeks or less. Since Red Broilers are more active than Cornish Rocks and grow slightly slower, they rarely experience leg weakness or Ascite, which is fluid in the body cavity. Red Broiler hens are not a good choice for efficient production of brown eggs.
They are not Freedom rangers though. They take something like 12 weeks for a 6# bird.
TSC will use a different hatchery based on where it is located geographically.