27 C.F.R. § 24.232 – Gauge of spirits.

(a) If the spirits to be used are in a spirits storage tank on bonded wine premises, or are received immediately prior to use from a distilled spirits plant not adjacent or contiguous to bonded wine premises, the proprietor shall determine the proof of the spirits and the quantity used by volume gauge or by weight. Upon completion of the transfer of spirit from the spirits storage tank to the spirits addition tank, the proprietor shall lock the spirits storage tank.
(b) If the spirits are received from the adjacent or contiguous bonded premises of a distilled spirits plant and are transferred directly into a spirits addition tank, the gauge of the spirits made on the distilled spirits plant premises will be used. The proprietor at the distilled spirits plant premises shall deliver a transfer record to the proprietor of bonded wine premises who shall acknowledge receipt of the spirits on the transfer record.
(c) If the spirits are received in packages and the quantity of spirits needed for the addition is not equal to the contents of full packages, a portion of one package may be used and the remnant package returned to the spirits storage room. The proprietor shall gauge the remnant package and attach to it a label showing the date of gauge, the weight of the remnant package, and the proof. The remnant package will be used at the first opportunity.
(Sec. 201, Pub. L. 85-859, 72 Stat. 1381, as amended, 1382, as amended (26 U.S.C. 5367, 5368, 5373))
(Approved by the Office of Management and Budget under control number 1512-0298)