B-25G and B-25H information on spent 75mm cartridges - through hatch or port?

kellyfamille · Jun 20, 2024

Looking at the operation of the 75mm in both the B-25G and B-25H how did the gunner remove or secure the spent casings? Were they ejecetd through a port or secured somehow in the ammo rack or other container?
Any help on this would be great.
Kellyfamille

Micdrow · Saturday at 4:36 AM

kellyfamille said:
Looking at the operation of the 75mm in both the B-25G and B-25H how did the gunner remove or secure the spent casings? Were they ejecetd through a port or secured somehow in the ammo rack or other container?
Any help on this would be great.
Kellyfamille

Orginially the spent cartriges where ejected out of the plane but after a cartrige hit another B-25 the practice was discontinued and spent cartriges where put back in the rack and unloaded after the plane has landed. Below picture of the ejection system from the book B-25 Mitchell The Magnificent Medium by N.L. Avery

Cannon Ammunition Storage Rack
A retainer in the upper rack held the noses of the rounds, and a selective lock in the lower of the rack secured their bases. The retainers could be inserted into three positions to accommodate the different lengths of the armor piercing, high explosive and smoke shells. The rack is capable of holding 21 shells. Used shell casings are returned to the rack once fired and disposed of later on the ground.

Pictures below of case

Micdrow · Saturday at 6:03 AM

3 pages from the Flight manual of a B-25G on how to fire the 75mm cannon. I think that answers all your questions

Have a great day

Paul

kellyfamille · Saturday at 8:33 PM

Micdrow said:
Orginially the spent cartriges where ejected out of the plane but after a cartrige hit another B-25 the practice was discontinued and spent cartriges where put back in the rack and unloaded after the plane has landed. Below picture of the ejection system from the book B-25 Mitchell The Magnificent Medium by N.L. Avery

View attachment 784699

Cannon Ammunition Storage Rack
A retainer in the upper rack held the noses of the rounds, and a selective lock in the lower of the rack secured their bases. The retainers could be inserted into three positions to accommodate the different lengths of the armor piercing, high explosive and smoke shells. The rack is capable of holding 21 shells. Used shell casings are returned to the rack once fired and disposed of later on the ground.

Pictures below of case

View attachment 784702

View attachment 784703

Micdrow thanks very much for this info.

kellyfamille · Saturday at 8:37 PM

Micdrow said:
3 pages from the Flight manual of a B-25G on how to fire the 75mm cannon. I think that answers all your questions

Have a great day

Paul

View attachment 784705 View attachment 784706 View attachment 784707

Paul
yes thanks this answers my query. Just FYI this comes about due to a surface find of a 75mm cartridge (M-18) near the north coast of Papua New Guinea (Buna-Gona area). The only reasonable explanation seems to be it was from a B-25.
Best Regards

Micdrow · Sunday at 6:27 AM

kellyfamille said:
Paul
yes thanks this answers my query. Just FYI this comes about due to a surface find of a 75mm cartridge (M-18) near the north coast of Papua New Guinea (Buna-Gona area). The only reasonable explanation seems to be it was from a B-25.
Best Regards

Morning,

Could have been thrown over the side of a B-25 that was damaged in combat or mechanical failure. It was comnon place to throw out everything possible to make it back to base once out of the combat area to keep the aircraft as long as possible.

Love to see some photographs of the casing.

All the best

Paul

MIflyer · Monday at 5:51 PM

The spent shell casings for the B-25G no doubt rattled around on the floor until the poor "gunner" (Navigator) had time to do something with them.

Read of one such mission in the Med. Of course the pilot wanted to get off as many rounds as possible during each pass and kept telling the navigator to load them faster. Finally, disgusted at not being able to hit much of anything, the pilot called for a course to head home. The navigator, stripped to to the waist, sweating profusely, and stumbling over the shell casings replied, "Fly, West, sir." The pilot responded that was not a proper course. The navigator went to his table, examined some maps, measured a course, and replied, "Don't fly West, sir. Fly 270 degrees."

The B-25H had a lighter version of the cannon, the T9, and it seemed to be sort of semi-automatic and could fire faster. The book "B-25 Mitchell The Ultimate Look" has extensive information on the cannon installation and procedures.

kellyfamille · Tuesday at 10:03 PM

Dear All,
Thanks for the information above.
I attach photos of the spent 75mm shell showing the head stamp for those interested.
Our research suggests it may be of Canadian manufacture under licence to the US.
Also shown is the current museum label describing the casing.
It is currently in the Kienzle Museum at the small town of Kokoda, Oro province, Papua New Guinea about 80km from the north coast.
It was found on the surface near Kokoda but as the label states no 75mm guns were used by the Australians in the Kokoda campaign. No US combat forces served in the area.
Hence our assumption that they have been ejected from a B-25 overflying the area.
Regards

ThomasP · 2024-06-26T06:00:05-0400

Hey kellyfamille,

FWIW

The 75mm M18 series cartridge case (75x350R) was not compatible with the M1 75mm Pack Howitzer. The Pack Howitzer used the 75mm M5 series of cartridge case (75x272R) as opposed to the M18 series. The '350' and '272' are the lengths of the cartridge cases in mm.

However, (leaving out the US made 75mm gun tanks and gun motor carriages) the 75mm M18 series of cartridge case was used with the various US manufactured 75mm field guns based on the French M1897 as well as with the British 75mm gun armed variants of the Churchill Mk VI & VII and Valentine Mk IX.

I do not know if the Australian forces used the 75mm field guns, and I do not think they received any of the Valentines with the 75mm, but they did test the 75mm armed Churchill and Sherman tanks in PNG (Wiki says the tests were performed in the Madang area). Also, the Australians used the 75mm armed Churchills after the war.

MIflyer · 2024-06-26T20:34:21-0400

kellyfamille said:
Hence our assumption that they have been ejected from a B-25 overflying the area.

The B-25 book says that initially the crews were told not to dump their empty shells out of the aircraft to prevent the Japanese from finding out about that armament. The 75MM was effective against ships and they would not have wanted the Japanese to know they could be hit by a 75MM.

B-25G and B-25H information on spent 75mm cartridges - through hatch or port?

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