Lee makes a 7mm 130 grain gas checked RN bullet mold.
It's been several years, but when I first started loading 7x57mm cast loads for Mausers this one gave me easy 1 1/14" groups at 100 yards out of several different rifles. It's as-cast diameter was .285, if I remember correctly.
At only $16 for mold AND handles, it's probably a cheap and easy way to see if you like it. Sizing die, lube pan, and punch are another $6.00. If it doesn't work, you can always get your money back at a gun show.
John