The tool pages below from Pacific Tool and Gauge makes mention of different Garand barrel crowns.
I was looking for pictures showing both but no luck yet.
tool and crown discussion '40-'67'67 and on crown toolI cut and pasted the relevant portion here from the first link above on Pacific Tool and Gauge;
"There has been some confusion over "pre-1964" and "1964" Crown Tools for the M1 Garand. Part of the confusion stems from the fact that M1 Garand production ceased in 1957. Another confusing factor is that the "1964" Crown Tool generates a three-faceted crown which matches the original M1 Garand, whereas the "pre-1964" Crown Tool generates a radius crown rarely seen on original rifles. The reason for these confusing designations is the manufacture of after-market replacement barrels for the M1 Garand. Until 1964, replacement barrels were manufactured with a "V-shaped" radius crown, based on a military specification. After 1964, automated machinery was able to economically replicate the original three-faceted crown.
The radius (pre-1964) crown may have slight advantages in accuracy, ease of cleaning, and ruggedness."
edit: I modified the name of the first link to reflect the 1940 - 1967 time frame and added the second link showing the 1967 and on crown tool.