On receipt of permit to compute the tax on TTB Form 5110.51, the revenue agent shall:
In the case of spirits in packages, prepare a gauge record as provided in § 26.164a in quadruplicate, compute the tax thereon, and attach all copies of the gauge record to TTB Form 5110.51;
In the instance of spirits in cases, verify by inspection the quantity of spirits described on the form; or
In the case of spirits in a bulk conveyance, verify by gauge or inspection the quantity of spirits described on the form.