  The nuclear recoil effect to the g factor of boron-like ions is investigated.
The one-photon-exchange correction to the nuclear recoil effect is calculated
in the non-relativistic approximation for the nuclear recoil operator and in
the Breit approximation for the interelectronic-interaction operator. The
screening potential is employed to estimate the higher-order contributions. The
updated g-factor values are presented for the ground 2P_1/2 and first excited
2P_3/2 states of B-like argon 40^Ar^13+, which are presently being measured by
the ARTEMIS group at GSI.
