Okay, I have one BIG concern, before we even talk about OAL, pressure, etc. You are not always going to be the owner of that rifle. One way or another, rifles tend to outlive their owners. Chambering a tube magazine rifle for a cartridge that's readily available in FMJ spitzer military surplus loadings may not be such a hot idea. That gun could wind up in the hands of someone that's not so gun-savvy someday, and they might stoke it up with the cheapest ammo to be found-military surplus. We have a responsibility to make sure that custom guns will be safe for future users, as well as ourselves.
The Brit's SAAMI pressure max is 45,000 CUP, but Speer says the 30-30 maxes out at 38,000 average CUP, and that's a big difference. Also, the 303 is about half an inch longer, and noticeably larger in both rim and body diameter. I'm no gunsmith, but I don't think this dog is going to hunt. :grin:
Time to start saving for that '95?