So what your saying is some commercial ammo in the 150 to 180 bullet range won't bend the operating rod. Or have you tried all of them. Have any of the manufactures changed the powder they use since you tested them?
It doesn't have to do with pressure as much as burn rate.
These guns were made and tested for powders available back in 1950.
Any newer powder or reformulated powder is suspect.
Hornady list 7 powders for 155 grain garand rounds and 14 for 30-06 rounds.
Only two powders are on both list and both are reduced 300 feet per second in the garand load.(Varget is 4.9 grains less in Garand)
So Hornady thinks twelve powders are not right for the garand.
go to walmart open a box of '06 and shake em and tell me what powder is in them.
And price a new operating rod at the next gun show just in case.
And I may be completely wrong.