Ordnance Instructions for the United States Navy. / 1866. Fourth edition. - United States. Navy Department. Bureau of Ordnance

The positions of the lock-lugs and their forms are verified by means of the bronze pattern furnished to each foundry for each class of the Dahlgren guns, and their dimensions by the templates. For other guns the position of the lock-piece is marked on the profile-board, and their measures taken as above.

The opening of the cascabel and its curves, and those of the breech and the muzzle-swell, are verified by means of the "cylinder-block" and the templates.

30. The following variations from the proper dimensions may be tolerated by the Inspector, though every effort should be made to conform exactly to the drafts furnished by the Bureau of Ordnance.

In the diameter of the bore			{	more			0.03
				less			0.00

Exterior diameter			{ {	where turned	}	more	.05
				or planed		less	.05
				where not	}	more	.20
				turned or planed		less	.05

In the length	{ {	of the bore, more or less					.10
		from rear of base-ring or line to face of the muzzle, more or less					.25
		of the cascabel, from rear of base-ring to the end, more or less					.20
		of the reinforce, more or less					.10

From the axis of trunnions to base-line, more or less							.05

In the length of chamber, more or less							.10

In the position of the axis of the trunnions			{	above axis of the bore			.00
				below axis of the bore			.20

In the length of trunnions, more or less							.05

Diameter of trunnions, less							0.05

In the same gun, no variations to be tolerated in the position of the trunnions, or in their alignment.
In the vent	{	diameter more					0.025
		do. less					.000

In lock-piece any dimensions			{	more			.10
				less			.00

Variation of position of exterior orifice of vent							.05
Idem of interior orifice of vent							.20

In the length	{ {	in the bore or vent					.00
		on exterior surface of reinforces, where turned or planed					.10
		elsewhere, where turned or planed					.25
		on trunnions, within one inch of rimbases					.10
		on trunnions, elsewhere					.25

Enlargement or indentation of bore by proof, not to exceed							.02

The measures are to be taken by scales corresponding with the standard measures of the United States.

If two or more cavities should be near each other on the exterior, the gun may be rejected, though the cavities should be of less depth than tolerated in the table.

If the trunnions are placed within the limits of toleration, the preponderance must not vary more than 5 per cent., more or less, from that fixed in the contract.

POWDER-PROOF.

31. The proof-charges shall be as follows:

Calibre and Class of Gun.			Charge of Powder.	Projectile.	Wads.	No. of Fires.
Shell-guns.			Pounds.
	XV-inch	43,000 lbs.	35	Shell 330 lbs.		3
			45	Shell 330 lbs.		3
			55	Cored sh. 400 lbs.		3
	XI-inch	16,000 lbs.	25	Solid shot	Gromet	1
	XI-inch	16,000 lbs.	15	Shell		10
	X-inch	12,500 lbs.	18	Solid shot	Gromet	1
	X-inch	12,500 lbs.	12	Shell		10
	IX-inch	9,000 lbs.	15	Solid shot	Gromet	1
	IX-inch	9,000 lbs.	10	Shell		10
	8-inch of 63 cwt., or	7,000 lbs.	12	Shot	Gromet	1
	8-inch of 63 cwt., or	7,000 lbs.	10	Shell		10
	8-inch of	6,500 lbs.	10	Shot	Gromet	10
	8-inch of 55 cwt., or	6,000 lbs.	10	Shot		1
	8-inch of 55 cwt., or	6,000 lbs.	10	Shell		10
	32-pdr. of	4,500 lbs.	8	Shot		10
Shot-guns.	130-pdr. of — cwt., or	16,000 lbs.	30	1 Shot	Gromet	10
	64-pdr. of 106 cwt., or	12,000 lbs.	20	do.	do.	10
	32-pdr. of 57 cwt., or	6,400 lbs.	15	do.	do.	10
	32-pdr. of 51 cwt., or	5,700 lbs.	13	do.	do.	10
	32-pdr. of 42 cwt., or	4,700 lbs.	10	do.	do.	10
	32-pdr. of 33 cwt., or	3,600 lbs.	10	do.	do.	10
	32-pdr. of 27 cwt., or	3,000 lbs.	9	do.	do.	10