5/16" tubing has gotten pretty expensive so I looked at 1/4" tubing and bought 50 feet of ebay which comes out to about 6.5 cents per inch. I am planning to make my own tubing to jacket die as it looks simple enough to do. I think there is couple ways of expanding .250" tubing to .262 - .263 diameter. One is by seating lead core which I think won't look pretty or come out uniform. 2nd way is to run expanding mandrel through cut up ~1" pieces which might need to be annealed first and have them strip off mandrel on return stroke. I've done this with thin 22 mag RF jackets and it worked well. It was easier setup because I used a shell holder to hold the case in place. I am thinking I can do similar thing to expand to 30 cal but I have no idea if this is going to work or not. Please share your experience / knowledge.