Centurion Gun Barrels

The Modern AFV discussion group is hosted by Erik Gustavsson and covers the variety of AFVs used by all nations in the post WWII era.

Centurion Gun Barrels

Joined: September 26th, 2009, 4:51 am

July 25th, 2012, 4:08 pm #1

Could anyone help with external dimensions for the 20 pdr (Type B) and L7 105mm barrels on Centurion? I've found a number of references which suggest that the 105mm was simply a bored out 20pdr, which implies that they were externally similar. It seems unlikely that there was enough "fat" in the 20 pdr to make it possible simply to bore it out. Grateful for help please.
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Joined: October 7th, 2005, 1:54 pm

July 25th, 2012, 6:22 pm #2

I think you may have misunderstood what happened with the development of the L7. The BREECH was retained, along with the mounting trunnions, to help facilitate a faster transition from the 20 pdr into the Centurion. The barrels are indeed different. While I csn't give you the dimensions, you can at least calculate total barrel and compare to kit barrels if you like. The actual barrel length should be
105mm x 52.
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Joined: September 26th, 2009, 4:51 am

July 26th, 2012, 1:25 pm #3

Rob - thanks for the helpful reply.

According to Richard Ogorkiewicz in his book Technology of Tanks, (London: Jane's Information Group, Ltd., 1991. ISBN 0-7106-0595-1), the L7 105 mm tank gun was developed in 1954 from the 20 pounder by "re-boring the tube". So I'm confused.

The Tank Museum displays both Ordance QF 20pdr and L7 105mm barrels. Photographs of them side by side appear to show that, fune extractor aside, they are very similar in length and diameter but maybe not the same.

I did some calculations based on your numbers for theoretical length and came up with these figures:

20pdr: 5,589mm
L7 105mm: 5,470mm

ie the L7 is 119mm shorter.

I've no figures for diameter but it looks as though both barrels have a double taper with a parallel centre section for the fume extractor and parallel sections at the muzzle. The breech ring fittings are known to be the same in order to achieve interoperabilty with a common breech.

So - was the 105mm a new design or a derivative of the 20 pdr and if so, what changed apart from the bore?

Thanks for any help given.

Stephen
Last edited by Stephen White on July 26th, 2012, 1:25 pm, edited 1 time in total.
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Joined: July 28th, 2005, 2:12 pm

July 26th, 2012, 2:32 pm #4

Stephen,

From what I remember the 105mm L7 was developed by RARDE Fort Halsted and was contracted later to Vickers Armstrong for initial production (main production was done by the ROF's), so I'm guessing that there is no direct design legacy connection between the L7 and the 20Pr. designs, and looking at the 20Pr. there is not enough material there to make an L7 from. I'm no gun expert but I do have examples of the ammunition for both in my collection and clearly these are very different weapons.

As Rob has said above the breech ring and mounting is common as is the balance of the completed weapon to allow it to fit Centurion with ease.

So I'm guessing new development.

Cheers,

Derek
Last edited by derekhansenataa on July 26th, 2012, 2:34 pm, edited 1 time in total.
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Joined: June 23rd, 2003, 4:53 pm

July 26th, 2012, 3:04 pm #5

Could anyone help with external dimensions for the 20 pdr (Type B) and L7 105mm barrels on Centurion? I've found a number of references which suggest that the 105mm was simply a bored out 20pdr, which implies that they were externally similar. It seems unlikely that there was enough "fat" in the 20 pdr to make it possible simply to bore it out. Grateful for help please.
While we're on the subject, can anyone confirm if these were the same length? Bovington has a Type A in a wall display which, although it's at an angle, it is potentially measurable but I've never had the chance to measure a dismounted Type B and I want to hang one off an Aussie M113 fitters' track after seeing some VT of one in the AWM years ago.

Rob
There's nothing cushy about life in the Women's Auxiliary Balloon Corps
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Joined: July 28th, 2005, 2:12 pm

July 27th, 2012, 7:44 am #6

Rob,

At least they should be to the end of the threads for the fume extractor and muzzle brake counterweights.
(I hope so as that's what I assumed when I turned our ones )

Derek.
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