No I'm not talking about the planet Vulcan that the Victorians never managed to find but to the humble 20mm Vulcan round that so many of us have had examples of in our collections. They so often end up in collections because there are loads out there and with the exceptions of the rare experimental types they're usually cheap. Unlike many collectors I've always found them interesting pieces so thought I'd show a few examples of the variations that are out there to be found.
The story goes that in 1939 the US army developed a .60 calibre anti tank cartridge. Early in the WW2 the engineers anticipated a need for a machine gun heavier than the .50 Browning and began to work on a .60 calibre gun that could fire a 1200 grain projectile at 3500 fps. The round was later necked down to .50 calibre and achieved a velocity of 3900 fps. Later on it was necked up to 20mm and became known as the .60/20 and fired a 1500 grain projectile at 3300 fps.
This later became the M50 series. It was built in several countries with dozens of different projectiles.
While the USAF in conjunction with the US Army was developing the M39 revolver and M61 Gatling runs to fire the M50 series of ammunition the Navy was working on its own aircraft gun designs. A twin barrel revolver designated Mk 11 was being developed and work was continuing on the Hispano-Suiza design, a new high performance variation known as of the Mk 12. In an effort to get the maximun case volume within the size constraints of the Hispano-Suiza receiver they utilised the case diameter of the calibre .60 and the length of the Hispano-Suiza or M90 series. This resulted in the Mk 100 series.
There were of course variations. Frank Marquardt developed for the American Navy Airforce a weapon that fired the 20 x 102 RG round, the cartridges were shot from a container having an electric primer in a much reduced head, a specially designed driving band was made to absorb the shock in order to prevent buckling of the case during this operation.
Further experiments were done to try and up gun the weapon using the 27 x 70B round but it was not adopted.
(info above taken from Dale Davis "Historical development summary of automatic cannon caliber ammunition 20-30mm".
All rounds shown below are INERT/empty/primers oiled or fired/fuzes unscrew etc.
20 x 102 Marquardt with container/wire links
27 x 70B
.60 cal
The one they were all developed from.
20 x 102.
A few of the variations. Amongst them you'll see APDS, practice, HE and test projectiles plus brass, teflon coated case (the green one), graphite coated alloy case (the grey one) etc. etc.
20 x 110.
Some of the variations of 20 x 110 round (for the sharp eyed amongst you yes I realise I have the wrong projectile in the graphite coated one, only realised after I uploaded the photo).
Variations together.
Another way of showing how they are all related is that the early rounds share very similar headstamps. The .60 cal rounds were simply re used and up necked to 20mm as required. Its always worth keeping your eyes open for Vulcan rounds with early headstamps, they're quite hard to find but are out there. Hope you enjoyed the photos, lets see what else you guys have to add to the thread by way of info/examples from your collections?:bigsmile:
The first photo shows from top to bottom:
27 x 70
20 x 102
20 x 102 Marquardt
20 x 110
.60 cal
The head stamps correspond t0 .60 cal on left and 27mm on right.
Thanks.
Dave.
The story goes that in 1939 the US army developed a .60 calibre anti tank cartridge. Early in the WW2 the engineers anticipated a need for a machine gun heavier than the .50 Browning and began to work on a .60 calibre gun that could fire a 1200 grain projectile at 3500 fps. The round was later necked down to .50 calibre and achieved a velocity of 3900 fps. Later on it was necked up to 20mm and became known as the .60/20 and fired a 1500 grain projectile at 3300 fps.
This later became the M50 series. It was built in several countries with dozens of different projectiles.
While the USAF in conjunction with the US Army was developing the M39 revolver and M61 Gatling runs to fire the M50 series of ammunition the Navy was working on its own aircraft gun designs. A twin barrel revolver designated Mk 11 was being developed and work was continuing on the Hispano-Suiza design, a new high performance variation known as of the Mk 12. In an effort to get the maximun case volume within the size constraints of the Hispano-Suiza receiver they utilised the case diameter of the calibre .60 and the length of the Hispano-Suiza or M90 series. This resulted in the Mk 100 series.
There were of course variations. Frank Marquardt developed for the American Navy Airforce a weapon that fired the 20 x 102 RG round, the cartridges were shot from a container having an electric primer in a much reduced head, a specially designed driving band was made to absorb the shock in order to prevent buckling of the case during this operation.
Further experiments were done to try and up gun the weapon using the 27 x 70B round but it was not adopted.
(info above taken from Dale Davis "Historical development summary of automatic cannon caliber ammunition 20-30mm".
All rounds shown below are INERT/empty/primers oiled or fired/fuzes unscrew etc.
20 x 102 Marquardt with container/wire links
27 x 70B
.60 cal
The one they were all developed from.
20 x 102.
A few of the variations. Amongst them you'll see APDS, practice, HE and test projectiles plus brass, teflon coated case (the green one), graphite coated alloy case (the grey one) etc. etc.
20 x 110.
Some of the variations of 20 x 110 round (for the sharp eyed amongst you yes I realise I have the wrong projectile in the graphite coated one, only realised after I uploaded the photo).
Variations together.
Another way of showing how they are all related is that the early rounds share very similar headstamps. The .60 cal rounds were simply re used and up necked to 20mm as required. Its always worth keeping your eyes open for Vulcan rounds with early headstamps, they're quite hard to find but are out there. Hope you enjoyed the photos, lets see what else you guys have to add to the thread by way of info/examples from your collections?:bigsmile:
The first photo shows from top to bottom:
27 x 70
20 x 102
20 x 102 Marquardt
20 x 110
.60 cal
The head stamps correspond t0 .60 cal on left and 27mm on right.
Thanks.
Dave.
