Q: What is "Mom AMF" in the beam check summary output?

A: This is the calculated bending moment modifier, as it appears in API-RP-2A-WSD 21st Ed., Eq. 3.3.1-1 in a slightly different format:

Mom AMF = 1/[Cm/(1-fa/F'e)]. That is the inverse of the part of the equation circled in red, i.e.

Q: How can I turn off any reduction in the x and y beam direction so that Mom AMF equals zero?

A: Although you cannot turn this reduction off, one can define a large Cmx and Cmy with the -cmfac option; e.g. &default -cmfac 1E4 1E4