Iron guns. The guns are first examined as to their proper dimensions, in which, in no case more than ³⁄₁₀ of an inch variation is allowed; and in the diameter of the bore only ¹⁄₃₀ from 42 to 18 pounders, and ¹⁄₄₀ from 12 to 4 pounders; but in the position of the bore ¹⁄₂ an inch out of the axis of a piece from a 42 to an 18 pounder, and ¹⁄₃ of an inch from a 12 to a 4 pounder is allowed. They are then fired twice with the charge in the following table, with one shot and two high junk wads; and examined with a searcher after each round. In this examination they must not have any hole or cavity in the bore of ²⁄₁₀ of an inch in depth, behind the first reinforce ring, or ¹⁄₄ of an inch in depth before this ring.
| Nature. | Proof charge. | ||
|---|---|---|---|
| Prs. | lbs. | oz. | |
| 42 | 25 | — | |
| 32 | 21 | 8 | |
| 24 | 18 | — | |
| 18 | 15 | — | |
| 12 | 12 | — | |
| 9 | 9 | — | |
| 6 | 6 | — | |
| 4 | 4 | — | |
| 3 | 3 | — | |
| 2 | 2 | — | |
| 1 | ¹⁄₂ | 1 | 8 |
| 1 | 1 | — | |
Iron guns are scaled with ¹⁄₁₂ the weight of the shot.
Brass guns. From 1 pounders to 12 pounders the diameter of the bore must not vary more than ¹⁄₄₀ of an inch, and in no dimensions more than ²⁄₁₀. The following are the established charges for their proof. The heavy and medium guns with a charge equal to the weight of the shot, except the medium 12 pounder, which is proved with only 9lbs. The light guns with half the weight of the shot. The brass ordnance have not however been proved of late with such heavy charges, but with the following:
3 Prs. light, 3 times, with 1 lb. each round.
6 Prs. light, 3 times, with 2 lbs. each.
12 Prs. light, 2 times, with 4 lbs. each.
12 Prs. med., 2 times, with 5 lbs. each.
Any hole ·15 of an inch deep upwards or sideways in the bore, or ·1 in the bottom, between the breach and first reinforce; or ·2 of an inch upwards or sideways, or ·15 in the bottom of the bore, before the first reinforce ring, will be sufficient to condemn them.
Brass Mortars and Howitzers. The exterior dimensions are in no respect to deviate more than ¹⁄₁₀ of an inch in an 8 inch howitzer, and ¹⁄₂₀ in the Cohorn mortars and howitzers. Their bores and chambers not to deviate from their true diameters or positions more than ¹⁄₄₀ of an inch.