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... he basically says words to the effect of: "we could have had it all very differently but basically the Air Ministry and the turret people just sort of didnt really bother themselves".
This isnt true.
Harris seems unaware of the extreme difficulty of building a workable 20mm top turret. The gun barrels of the Hispano-Suizas are very long and exert a tremendous force when traversed toward the side. Remember, you get lever arm effects, which are oh so fun for the engineers to work with.Brits didn't have 50 cal turrets or cannon turrets for a combination of reasons. I think what Harris said quoted above is basically nonsense. (As In I'm sure he did say that but it doesn't tally with the air ministry files). There was a big supply issue early on with 50s and the cannon turrets were so heavy it necessitated reducing the bomb load to the level where it was calculated that you'd need to fly more planes over the target and you'd end up with the same aircrew losses anyway. I'm not 100 percent sure I agree with all the reasoning but that was how it was discussed at the time.
We have some confusion as what is a cannon and what is a machine-gun. Some countries changed the definitions a bit but in general machine guns were under 20mm and cannon were 20mm and up. 15mm guns are a bit iffy.What's the largest non-cannon machine gun round used in ww2 aircraft? Some sort of 30mm solid shot?
This is regardless of the type of projectile, a solid shot projectile does not turn a cannon into a machine gun.
A major difference for most people was the construction of the projectile
View attachment 693130
Machine guns (small arms) tended to use a jacket material that would upset on firing to fill the groves (or swage down).
Cannon , because of the steel shell bodies, just about always used "driving bands" usually copper unless shortages required soft Iron. The projectile rode on the lands of of the rifling and only driving band engaged the rifling and got engraved.
View attachment 693131
Obviously fitting driving bands required a lot of work/machining.
cannon is not a synonym for gun that fires HE ammunition.
One problem with using this as a demarcating for what and what is not an autocannon is that the 13x64B round used in the MG-131 has a driving band, while the much more substantial 14.5x114mm ammunition used in the KPV and friends does not, meaning that the smaller and weaker of the two is the autocannon while the larger and far more powerful of the two is the mere heavy machine gun.
A major difference for most people was the construction of the projectile
Yes there are cross overs.Machine guns (small arms) tended to use a jacket material that would upset on firing to fill the groves (or swage down).
Cannon , because of the steel shell bodies, just about always used "driving bands" usually copper unless shortages required soft Iron. The projectile rode on the lands of of the rifling and only driving band engaged the rifling and got engraved.
I believe the largest machine gun round was in the 13mm range and the smallest cannon round was in the 15mm range.
Except the left over WW I ammo is NOT what you want to be shooting at aircraft even if you keep the .303 guns.How about simple economics. There were millions of .303 rounds left over from WWI.
It is not even the nitro-cellulose, old wartime brass had tendency to split or crack upon firing.Yeah my understanding is that newer, nitro-cellulose ammunition was always used by the RAF vs. all the old cordite.
Agreed.You want the best quality ammo you can get for aircraft guns.
Agree, but with high stocks of WWI ammo it was available distribute it to the ground troops. That would free up .303 production facilities to lean heavily in production of aircraft rounds till the entire logistics system caught up. Also the large scale production of the .303 BMG was also in place but not for .50BMG rounds delaying the introduction of the large Browning on aircraft.Except the left over WW I ammo is NOT what you want to be shooting at aircraft even if you keep the .303 guns.
No left over incendiary ammunition.
No left over armor-piercing ammunition
and having aircraft guns jam because you are using cheap, 15-20 year old ammo is truly false economy. The whole idea of going the Browning was to allow the guns to be mounted out of arms reach of the pilot. Once a gun out reach of the pilot jams it pretty much stays jammed until the plane lands.
HiIt is not even the nitro-cellulose, old wartime brass had tendency to split or crack upon firing.
It is one thing to have a few problems (2-3 bad rounds per thousand) in bolt action rifle.
In an eight gun fighter that is carrying 2400 rounds having the same failure rate could jam 50% of the guns or more.
You want the best quality ammo you can get for aircraft guns.