Mud in gun barrels

[gmerkt]

Do wing mounted .50 machine guns count for the "General Firearm Discussion" thread? Mods, feel free to move it.

When the Japanese were trying to take Papua New Guinea away from the Australians, early in the campaign there was a battle at Milne Bay on the eastern tip of New Guinea. The Aussies built three airfields there to provide close air support for their ground forces. The US had sent some Lend Lease Curtis Kittyhawk fighters to Australia in early 1942, and some of these were used at Milne Bay. These were the equivalent of the US P40E with six .50 machine guns in the wings. Here is an except from the book, Touched with Fire, by Eric Bergerud and is from an interview with William Garing, who was commander of all air forces at Milne Bay:

"It was dreadful country, with only a tiny airstrip between coast and Stirling Mountains. We had very heavy rain every night. And the mud was almost indescribable. There was no pavement or proper drainage. There was steel matting to provide strength, but it was covered with a layer of liquidy mud, We had two squadrons there instead of the one the strip was built for, so it was crowded with our Kitty Hawks. When they took off you could hardly see the plane. A cascade of mud came up the sides and to the rear. Landing was the same, just a spray of mud. It got into everything. It would get into the guns and within a few days the gun barrels were a millimeter above size. [Keeping machine guns and artillery clean was crucial. If mud or dust got into them, firing the weapon would cause abrasion, which increased the diameter of the barrel. The increased diameter of the barrel lowered the velocity of the bullet and lessened its spin, causing potentially serious loss in both range and accuracy. As it was, barrels were changed at intervals. - EB]"

During this battle, because the air strips were so close to the scene, pilots were flying up to six sorties per day so the guns were in use a lot.

The name is pronounced, MILL-in or MILN. The E is not pronounced.

Even thought the P-40 was an older design when the war started, it was produced up to Nov.1944.

Years ago a retired colonel told me a WW2 story about a squadron in his group that was to be re-equipped with a different fighter type. I can't remember if it was in the 5th or the 13th Air Force, but it was in the Far East. This squadron had been flying P-38's and were scheduled to get P-47's. They complained, their squadron commander took the complaints to group HQ, and what they got instead of P-47's were P-40's.

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[Outpost75]

It was SOP to stretch an unlubricated Trojan condom over the muzzles of machine guns to keep insects, sand, mud and dust out of them. A standard condom fit over the barrel of a .30 Browning just fine.

A special larger version was made for the .50 Browning. These were gleefully repurposed for propaganda value and distributed to local brothels ahead of the arrival of American troops.

 

[bcp]

I suspect the author wasn't familiar with the erosion rate of an aircraft machine gun's lightweight barrel under heavy usage.

A quick search said the P-40 used mid-200's cartridge capacity per gun, and that expected barrel life was about 3000 rounds. Six sorties per day (6x250=1500 rounds per day) could wear out a barrel in a couple of days.

That's more likely than mud in a barrel causing erosion but not a barrel burst.

Bruce