Well, Jim, you may have to wait a while. I shopped earlier in the week for a 1.175" aluminum bushing for my brownells barrel vise. Thought I had one coming but no-dice, backordered. I'm gambling that the no. 5 steel bushing will work - it's in stock. Brownells says it fits Mauser 98 military barrels, which best I can find on the interweb is 1.2", same as the 03a3. Am I wrong?
Now, I've never used a steel bushing before. Can I wrap aluminum tape on the barrel to prevent damage to the finish, same as I do on the action?
For anyone else that stumbles on this now, Chuck's thread is a must read, although his equipment is a bit more than my DIY shop. For convenience...https://www.milsurps.com/showthread.php?t=26677