27 C.F.R. § 30.63
When the weight or proof of a quantity of distilled spirits is not found in Table 2, the proof gallons may be ascertained from Table 3. The wine gallons (at 60 degrees Fahrenheit) may be ascertained by dividing the proof gallons by the proof.
Example. A tank car of spirits of 190 degrees of proof weighed 60,378 pounds net. We find-
| Proof gallons | |
| 60,000 pounds equal to | 16,778.4 |
| 300 pounds equal to | 83.9 |
| 70 pounds equal to | 19.6 |
| 8 pounds equal to | 2.2 |
| Total | 16,884.1 |
That is, the total weight of 60,378 pounds of spirits at 190 proof is equal to 16,884.1 proof gallons. The equivalent gallonage for 70 pounds is found from the column 700 pounds by moving the decimal point one place to the left; that for 8 pounds from the column 800 pounds by moving the decimal point two places to the left.
Example. A package of spirits at 86 proof weighed 3211/2 pounds net. We find-
| Proof gallons | |
| 300 pounds equal to | 32.7 |
| 20 pounds equal to | 2.2 |
| 1 pound equal to | .1 |
| 1/2 pound equal to | .1 |
| Total | 35.1 |
That is, 3211/2 pounds of spirits at 86 proof is equal to 35.1 proof gallons. The equivalent gallonage for 20 pounds is found from the column 200 pounds by moving the decimal point one place to the left; that for 1 pound from the column 100 pounds by moving the decimal point two places to the left; that for the 1/2 pound from the column 500 pounds by moving the decimal point three places to the left.
Fractional gallons beyond the first decimal ascertained through use of this table will be dropped if less than 0.05 or will be added as 0.1 if 0.05 or more. The wine gallons (at 60 degrees Fahrenheit) may be determined by dividing the proof gallons by the proof. For example: 35.1 divided by 0.86 equals 40.8 wine gallons.
27 C.F.R. § 30.63
Sec. 201, Pub. L. 85-859, 72 Stat. 1358, as amended ( 26 U.S.C.5204 )