Colt 1903 Failure to Extract

[EMC45]

My suggestion is to take a Cerro Safe casting of the chamber and "mike" it compared to a factory round and the published chamber spec for the 1903. If this chamber has been polished (sounds like it) it may have been over zealously done. Your description of "any barely visible rifling" makes me think the gun was shot with corrosive ammo and then not cleaned. Maybe even for decades.

I had a 1908 (.380) that had a similar rough bore....It ran fine though.

 

[piratebob64]

I have and do own multple 03 and 08 colts, i had one that did what yours did, just get another barrel.
Actully had extrators break in half in them.