7mm rum into 300 rum

[remcraz]

This might be the dumbist question on this site but I have a lot of 7mm rum brass. The question is can I size it into 300 rum or is that to much stretch
Thanks

 

[Lefty7mmstw]

This might be the dumbist question on this site but I have a lot of 7mm rum brass. The question is can I size it into 300 rum or is that to much stretch
Thanks

half of my 300 rum brass is actually 7 rum brass. You may have a few necks crack on the first firing. I suppose annealing could help with that.