  The hyperfine effect in muon capture rate is analyzed with taking into
account of the second-order terms in 1/M in the non-relativistic Hamiltonian.
It is shown that in the situation of the dominance of the squared first-order
terms the interference of zero-order and second-order terms has no significant
influence. General expression for neutrino (recoil nucleus) angular
distribution in muon capture by nucleus with non-zero spin is proposed. High
sensitivity to $g_P$ of the term related with alignment of the initial mesic
atom is discussed in the approximation of dominating Gamow--Teller matrix
element.
