Putting 8 and 8 together; Adrian, comment?

[cannonmn]

On and off over the past few years I've tried to find out why one particular British light 3-pounder bronze gun was rifled, probably more than a half-century after it was cast.  The previous theories I've had and documents I've looked at really don't matter since they were all dead-ends.  The answer, although not yet proven, may have dropped in my lap from a most unexpected source. 

A friend sent me photos of a rifled ship's cannon with a 2.6-inch bore, rifled with eight shallow grooves and eight lands, lands and grooves of equal width.  The gun was made by Sir W.G. Armstrong and Co., of England.  Its serial number seems to indicate a date of manufacture in the late 1860's, but I haven't yet pinned it down.

The rifling in the 3.1-inch bore of the bronze 3-pounder (dated 1796) appears identical in form to that in the 2.6-in. iron or steel gun.  Therefore, my latest theory holds that the bronze gun was purchased as government surplus and rifled by Sir W.G. Armstrong & Co., for sale to any shipowner who needed armament for his vessel.  The bronze 3-pounder came to us originally mounted on an antique ship's carriage which fit the tube perfectly, and is made of the same color of wood as that used in the carriage that's under the iron or steel gun.

Eight-groove rifling of this type isn't at all common; I only found one reference to eight-groove rifling in some reports of US Army cannon tests, and other characteristics of that rifling don't match the two examples of rifling described above.

What kind of projectile either of these weapons fired is another question I'll have to tackle as a separate project when I have more time.

Any thoughts on any of this, anyone?

Two photos of British Army bronze 3-pounder gun with later rifling (later incorrect carriage):   





Three photos of small ship's rifled pivot gun made by Sir W.G. Armstrong & Co.

 

[A.Roads]

Thta is certainly an interesting & desirable bronze gun. Has it the GR3 cyhper? 3 prs dropped off the general issue list by about 1800 if I recall correctly - though I have seen an iron example dated 1803.
To find some documentation that will explain its particular past will probably be nigh on impossible I should think, but you never know if you don't seek! I would suspect that you are correct in your surmising that it has been rifled in the late 1860s period onwards, its rifling is looking away from studded projectiles which mechanically engaged the grooves upon loading & towards an expanding base plate.
However given the massive size of Armstrong's operation, we are talking production on a vast scale of very large pieces of ordnance up to 100 ton RML guns - also he was having to defend his choice of metals to some extend (mainly his extensive use of wrought iron in lieu of steel, made viable with the Bessemer process which was a hugely important discovery) I really doubt that he would have included the purchasing of small, obsolete bronze guns & their conversion into rifled pieces for what must have been a very small commercial market. I would think that this would have instead been done by a much smaller concern, trying to capture some business by upgrading such pieces with modern rifling.  Are there any markings regarding the conversion from SBML to RML? 
Adrian

[cannonmn]

Adrian, thanks for the info.  I have a friend in the US who studies British 19th C. rifled artillery, who shares your opinion that this seems to be an unlikely project for Armstrong.  He thought Blakely was a possibility, I guess since Blakely did convert a number of older British smoothbores, such as some now in the collection of the Naval Historical Center at the Washington Navy Yard.  Still, I need to find other pieces with the same type of shallow 8-groove rifling before I try to make a match.  Offhand, I don't know of such a piece attributed to Blakely; if anyone does please let me know.

As far as I can see there are no marks on this that relate to its conversion, but as I recall there is another number underneath near the trunnions which may have some meaning in that context if this type of British 3-pounder doesn't normally have marks in that location.

If you want to look at the marks on the piece, there is an early, kind of low-quality video we did, which shows the marks at about 4 minutes into the video.  I mis-identify the MGO as "Cornwallis" when the "C" actually stood for someone else, I think, so straighten us out on that please.

We made another mistake in letting Ed get his face too close to the vent when lighting the fuse-we don't do that anymore.

Regarding the 3-pounder production, I've seen pieces dated as late as 1808.  Somewhere we have a shorter 3-pounder bronze gun, British, still smoothbore, which has built-up trunnions.  It came from Africa, so perhaps it had to be adapted to a larger carriage at some point.  As I recall it has same marks on breech and chase as the gun shown in the video, but different maker.

http://www.youtube.com/watch?v=lhER53Mb_T4

[cannonmn]

I think I have the answer thanks to the Brits:

http://www.palmerstonforts.org.uk/smforum/index.php?topic=137.0