What brand? Serial number range?
What's the condition of the barrel? Is the bore bright, frosted, dark?
Does it have pronounced rifling? How about throat and muzzle erosion?
Are all parts manufactured in the same timeframe by the same manufacturer?
There are websites that will tell you the serial number range for all the different M1 Garand manufacturers.
They will also give you the drawing numbers for all the parts that were correct for that serial number range.
Many Garands were re-barreled after the war and many are mix masters put together with many different parts.
Just because it looks old and beat up doesn't make it special. Millions of these were made during WW2.
I picked up a Springfield for less than $1,000 with a crappy barrel.
I am re barreling it at the upcoming M1 Garand clinic in Petawawa on the 30th of the month.