Artillery Question

[Tim Birch]

From time to time I have seen references to captured guns being bored out to a larger calibre. Is it also possible to resleeve a barrel thus reducing the calibre?

Presumably factors like the thickness of the barrel are important in calculating the maximum explosive force it can withstand within it, and if is the case, does tampering with it such as boring out, weaken it and increase the risk of a burst?

Tim

[Ralph J. Whitehead]

Any type of alteration to a forged steel item would weaken the integrity of the steel, especially if you make the artillery tube thinner. It would be subject to fracturing more, especially in colder weather.

My father was in the Marine Air Corps in WWII, when he was returned to California after serving in the Pacific they did not know what to do with him. He and another Marine mechanic were given the task of replacing every rivet in a B-24 with new ones. While both men were professional sheet metal workers before the war he always said that he would never fly in that plane if it was going to take off after their work.

Ralph

[Robert Dunlop]

Is it also possible to resleeve a barrel thus reducing the calibre?

I guess that technically it is possible. Presumably, it would require boring out the rifling and leaving a tapered bore into which a slightly conical sleeve could be inserted. I am not aware of any instances of this being done on a large (or even one-off scale), for what that's worth. Obviously, civilians and some individuals in the army did take an interest in prototyping and even small scale production of weapons. From the British perspective, it is possible that one of the engineering facilities in France could have done it, such as the Second Army Workshop in Armentieres. They produced some interesting inventions and were involved in customising some weapons. They even had facilities to recycle shell casings, etc and produced relatively large qualities of grenades and mortars for example. However, the general principle seems to have been not to produce anything that required high tolerances or significant work of this nature unless it was experimental work and the potential gain was perceived to be high.

[Mike_H]

Tim

Yes this was done. An example is the 13pdr 9cwt Anti-Aircraft gun. These were 18pdrs (3.3" calibre) relined to 3". There is one on the Thornycroft 3 ton lorry on displayat IWM Duxford. Externally the barrel and recuperator are identical to a normal 18pdr.(It's on a high angle mount of course)

Yours

Mike

[Greg]

With the 18 and 13 pounders the barrel consisted (according to Ian Hogg) of an inner barrel wound with wire under tension and this was placed inside an outer which was shrunk on.

This system would presumably make calibre alterations easier.

I was under the impression that the 13 pounder was 3 inch calibre and that this was the base piece for the 13 pounder 9cwt anti aircraft gun. The 3inch 20cwt was a completely separate gun based on a naval mounting.

The 18 pounder was apparently modified in US service first to US 3 inch and then to fire French 75mm ammunition

Source Hogg I., Teh guns 1914-18,Pan Ballantine 1971

Greg

[Bob H]

I only have information on naval guns and have examples of both increase and decrease of calibre.

When the Italian Navy rebuilt their four remaining WW1 battleships in the 1930's, their 12" guns were bored out and relined to 320mm (12.6").

In 1914 the old battleship HMS Redoubtable (ex Revenge) had her obsolete 13.5" guns relined down to 12" to suit the supply of ammunition used by most of the older battleships. She was then used in several operations off the Flanders coast, bombarding German positions in 1914/15. She was finally replaced with shallow draught monitors at the end of 1915.

Photo's of guns being machined after relining can be seen on this site:

http://members.lycos.co.uk/RoyalArsenal/pabilljoem.htm

[Gilgamesh of Uruk]

One of the 15" B guns (i.e. an 18" gun) was retubed down to 16" for proof firing & testing - and may then have been used in one of the WWII shore batteries at Dover.