Cannon Barrel lengths. Are there any references on this subject?

[brunnels]

I'm currently working on The Pegasus kit from Amati/Victory models, and I have decided to print a set of new cannons to replace the cannons the kit came with.  While looking through the 3d Cannon print files in the NRG Resources, I noticed there were quite a few barrel lengths for the Armstrong-Fredrick 6 pounders.  How does one determine the barrel length appropriate for any certain vessel?  Are there any reference materials that will have this information?  I can't seem to find much info on the topic online or in any of my books.  I assume smaller vessels had shorter cannons due to deck size limitations and vice versa, but surely the English standardized this to some degree.

[barkeater]

There was some variation in length for a given ball weight. Larger canons were longer and would be placed on lower decks for stability. I have never heard of shorter gun barrels for small vessels in the same shot weight. Rather the shot weight determined the length with some manufacturing variation. Smaller vessels naturally had smaller weight canons and larger vessels would have multiple canon sizes with larger on the lower decks

Rich

ty. 

[Thukydides]

There was quite a bit of variation in length of the cannons and there is likely no way to know what exact lengths were on Pegasus. In fact it is likely there was more than one length of cannon on her. That being said, I would recommend taking a look at Caruana's book on English sea ordinance (it is very expensive but you might be able to borrow it through your local library). He discusses the issue in detail and makes some general observations as to which lengths were used on which ships at which times. I will try to remember to take a look when I get home to see if he has anything to say about sloops in the late 18th century.

 

The fully framed model books on the swan class ships which you can get from seawatch books likely have a discussion of the cannons. The authors did tonnes of research for those books so I would defer to whatever they have to say on the subject matter.

 

@thibaultron has made available some very nice models of guns which you can find here:

 

 

Finally, I have transcribed one set of dimensions from 1780 which I include part of below just in case you find them helpful. It has dimensions for three different sizes of 6pdrs.

1780 Gunnery Tables by Thomas Walton

Source: RAM G3n/35a; Caruana, English Sea Ordnance, 218-219.

Date: November 1780

 

DIMENSIONS of the EXTERNAL parts and CALIBRE of IRON GUNS of each NATURE and LENGTH in INCHES and DECIMALS.                  November 1780
Nature		9			6			4		3
Length in Feet		8½	7½	7	9	8	6	6	5½	4½
	On the Base Ring	17	17	17	15.88	15.8	15.5	13.6	13.6	11.6
	Before the Base Ring	15.16	15.3	15.4	14.3	14.[0]	13.85	12.1	12.05	10.55
	On the First Reinforce Ring	14.7	14.76	14.84	13.55	13.5	13.52	11.75	11.84	10.2
	Behind the First Reinforce Ring	11.2	14.36	14.2	12.97	13.0	13.02	11.3	11.34	9.8
	Before the first Reinforce Ring	13.34	13.42	13.4	12.2	12.25	12.18	10.57	10.57	9.3
	On the Second Reinforce Ring	13.15	13.25	13.22	12.0	12.05	12.05	10.52	10.57	9.15
	Behind the Second Reinforce Ring	12.63	12.75	12.8	12.52	11.55	11.55	10.25	10.07	8.75
	Before the Second Reinforce Ring	11.76	11.86	11.7	10.7	10.7	10.67	9.3	9.3	8.25
	At the Muzzle Astragal	10.16	10.15	10.5	9.2	9.2	9.35	8.18	8.18	7.15
	At the swell of the Muzzle	13.15	13.25	13.3	11.87	12.05	11.95	10.4	10.52	9.[?]
Thickness of Metal	Before the Base Ring	5.47	5.54	5.59	5.32	5.27	5.09	4.44	4.42	3.[?]
	At the Muzzle Astragal	2.97	2.97	3.14	2.77	2.77	2.84	2.48	2.48	[?]
	At Charging Cylinder above the Calibre	1.26	1.33	1.38	1.66	1.61	1.43	1.23	1.21	[?]
Distance	From behind the Base Ring to the hinder parts of the Trunnions	3:5:61	3:0:51	2:9:9	3:8:45	3:5:1	2:5:01	2:5:24	2:2:66	1:8:[?]
	From behind the Base Ring to the First Reinforce	2:5:14	2:1:7	2:0:0	2:6:8	2:3:4	1:8:56	1:8:56	1:6:8	1:5:[?]
	From behind the Base Ring to the Second Reinforce	2:0:93	1:9:5	1:7:8	2:3:18	1:11:76	1:4:9	1:5:35	1:3:63	1:0:5
Diameter of the Calibre		4.21			3.66			3.21		2.91
[???] equal [???] parts of the Calibre		4.8			4.175			3.68		3.312

Edited September 25, 2025 by Thukydides

[Bev]

 

Calibers and lengths of principal eighteenth century English cannon

Caliber	Field		Ship				Siege		Garrison
	Iron		Bronze		Iron		Bronze		Iron
	Old	New	Old	New	Old	New	Old	New	Old	New
1-1/2-pounder							6'0"
3-pounder	3'6"	3'3"		3'6"	4'6"	3'6"	7'0"		4'6"	4'2"
4-pounder					6'0"
6-pounder	4'6"	4'1"	8'0"	4'4"	7'0"	4'4"	8'0"		6'6"	5'3"
9-pounder		4'8"		5'0"	7'0"	5'0"	9'0"		7'0"	6'0"
12-pounder	5'0"	5'1"	9'0"	5'6"	9'0"	5'6"	9'0"	6'7"	8'0"	6'7"
18-pounder		5'10"		6'4"	9'0"	6'4"	9'6"	8'4"	9'0"	7'6"
24-pounder	5'6"	6'5"	9'6"	7'0"	9'0"	7'0"	9'6"	8'4"	9'0"	8'4"
32-pounder				7'6"	9'6"	7'6"	10'0"	9'2"	9'6"	9'2"
36-pounder				7'10"				9'6"
42-pounder			9'6"	8'4"	10'0"	8'4"	9'6"	10'0"		10'0"
48-pounder				8'6"		8'6"		10'6"

[Lieste]

For the most part 6 pdr were either 7ft (heavy line ship qtr deck) or 6ft (lighter vessels and qtr decks of frigates etc). 

Earlier guns tended to be longer, but smaller quantities of stronger powder could get the same results from shorter pieces as older longer guns using heavier but weaker powder charges. Moreover, an excessive muzzle velocity requires a heavy gun, wasteful powder usage and makes relatively little difference to downrange performance, especially in smaller shot sizes. Even the lightest of these have quite benign recoil performance, which is the main advantage to a slightly longer/heavier piece. There is also a longer sight along the line of metal which can make consistent pointing a hair easier for a longer gun, but this is unimportant.

Light Field guns are a bit shorter than the 'it doesn't matter' level, and are also too light to be controllable with full distant charges. This still doesn't matter 'very much'.

For merchants and other very small vessels there are non-Ordnance board 'cutts' or light guns from various foundries which can throw a 6pdr shot with less weight on deck, and mostly this won't matter as much as the very small numbers carried, or the roughly 20 shots per gun minimum (compared to 80-110 for a fully stowed warship) of ammunition, which precludes these winning a protracted engagement.

I'd plump for 6ft, if there is no additional information on the gun weights or length in the literature for your ship.

[thibaultron]

One way is to measure the cannons that came in the kit, and use the overall length in the spreadsheet to determine which files to print.

[Lieste]

That works if the kit parts have an appropriate size, just lacking finesse or numbers... this is sometime not at all true, being mere suggestions of 'gun'.

[thibaultron]

True, but if it is all you have, at least they will fit the kit parts.