Yep. Lots of places sell different sizes, you can buy just numbers or letters. Maybe do a -1 instead of R and no letters needed. Sets cheap typically though.
I've punched lots of brass disks with different sizes. Practice, draw a line with a pencil if hand stamping, reset in the mark after every strike. Harder hits not always better. Depending on curve, multiple hits to fill in. But nice results can be had.