49 C.F.R. § 299.327 – Rail end mismatch.

Any mismatch of rails at joints may not be more than that prescribed by the following table:

Table 1 to § 299.327
Track class	Any mismatch of rails at joints may not be more than the following:
On the tread of the rail ends(mm)	On the gauge side of the rail ends(mm)
H0	6	5
H1-H2	4	4
H3-H7	2	2