Don't really understand all this. If I am reading right, a .300 diameter bullet will not go into the chamber. If this is correct, no bullet is going to load in it jacketed or cast. The barrel has a problem. Now the rest of your post makes it sound like the length is too long to chamber. I just bought a 30-30 barrel from Ed and a .308 jacked bullet chambers, so again the barrel must have a problem if a 300 diameter bullet will not go into the chamber. Now the barrel I bought has a very short throat and it is very easy to set the bullet a little off the rifling. Matter of fact using a Seirra 130 SSP bullet I had to seat the bullet a little shorter than the book said to get it .030 off the rifling. Factory 30-30 chambers fine. By my research, the older 30-30 barrels had the long throat and the newer barrels are better.
Next thing you know everone is mad because they think the poster said something bad about Ed. I did not read anything bad about Ed, the poster just stated that he ordered the barrel from Ed. I think the real reason everyone is mad is because their opinion is being questioned. If your barrel has a problem which is sounds like it does from the way you wrote your post, send it to T/C and get it fixed.
Now my word of advice. I would not make a decision to buy a barrel based on what anyone here says. If you pay attention, post asking for hard core advice about a problem usually get an answer, but very few. Posts asking about opinion get a lot of answers, but they are just that, opinion. You might want to check into the opinions, but do your own research to make your decision. Personnal I would never shoot cast bullets in a 30-30, so all the opinions would mean nothing to me.
Good luck getting your barrel problem fixed.