I have a "solid" (ie heavy) barrel in .30-06 for my Mauser M03.

Originally I was planning to sell it. Still might.

Q1. Recently was thinking could a M03 barrel be re-bored and/or re-chambered?

That is the first question for gunsmiths or other knowledgeable members.

Is there any issues with reboring an existing barrel such as the M03 has? I can post photos if need be.

Q2. What cartridge and bore?

Point 1. The barrel is a heavy version which means lots of meat. So thick so should not be many problems with a bigger bore size.

Point 2. This means smaller calibres may mean the barrel is still un-necessarily heavily, IMO.

Point 3. The Mauser M03 has different removable bolt heads in the bolt heads for the families of cartridges of: .222; .30-06; magnum and 8x68S; .404 etc. Have to check if any others.

Point 4. Similar for magazines.

So it possible a wide range of options are possible.

Point 5. Have to re-look at the barrel. Don't think it has open sights? Will have to check. Checked on the photo above, yes it has the standard crappy Mauser open sights.

Point 6. Will have to measure the barrel thickness and length.

First I was thinking of the .318 Westley Richards in .330. No problem I think with using the .30-06 magazine or bolt head. My "Tiger" rifle project is on hold due to funds being short at the moment. A .318 would be cool for BGRC shoots as a minimum calibre for some comps. But maybe the barrel would still be annoyingly heavy for hunting.

Secondly I would love a 9.3x62. It would also be milder for such BGRC shoots where I use a .375 H&H currently. Would the rifle still be too heavy? I don't want a heavy rifle in this calibre.

Thirdly the heavy barrel got me thinking. I already have a .404 barrel and 8x68S barrel. Could something like a big bore version of the x68S be possible? A 10.5x68 perhaps?

Fourthly, I wonder if something in a .500 or similar is possible on the rifle and one of the bolt heads? I prefer not getting into magnum rims, but maybe?

If a .500 or similar was possible that would be truly cool.

Have a brainstorm and look at the specific questions, specific points and tell me what you think or know. Thanks.