Slamfire, great info.
Polytetrafiuoroethylene is a polymer known in the trade as Teflon.
https://patents.google.com/patent/US2972947?oq=polymer+coated+rifle++cartridge
After reading parts of the patent, high pressure would be the cause.
Hatcherites- Followers of Hatcher's Notebook.
Great reference! It shows that nothing is new under the sun, sintered telfon coatings go way back.
This is from the patent:
It has been recent practice to lubricate ammunition for aircraft mounted 20 mm. automatic rapid fire guns with oil or grease to obtain improved operation of the gun through decrease in jamming and icing. While the measure has been a success from the standpoint of lubrication, it has brought with it serious maintenance troubles. A lubricating coating of oil or grease on the cartridge case provides a medium for the pick-up and retention of dust, deposits from blown-back gases, sand and moisture. Dust and sand adhering to the cartridge case may cause abrasion and jamming of the gun and feeder mechanism and excessive wear of the gun barrel. Accumulated dispersed or emulsified water on the cartridge case sometimes thickened rapidly in cold weather and invited icing troubles. A high viscosity oil is used for lubrication of the cartridges in order to avoid rapid drainage. This oil through blow-back accumulates in the gun mechanism where it blends with the low viscosity oil used for lubrication of the gun mechanism to produce a mixed oil of undesirably higher viscosity from which operational difficulties develop at low temperatures. A further disadvantage is that oil or grease must be applied to ammunition at a time as close to firing as possible because of difficulties arising from draining and evaporation of oil, uneven distribution of grease and accumulation of dust and water on the oiled or greased surface. While oiling of ammunition has been satisfactory in some respects, the time and labor required to lubricate ammunition just after belting prior to mounting in the plane is a military drawback. Wax coating of ammunition is only partially successful due to plastic flow of wax and adhesion between cartridges during storage prior to belting and to accumulation of dirt. The problem of coating and storing waxed ammunition has always been a nuisance and at times has proved costly. Up to the present no wholly satisfactory solution to the problem of lubricating ammunition has been found.
The 20mm anti aircraft gun mentioned in the patent is this one, or rather, this is one of a huge class of 20mm automatic cannons:
They are all over the forward deck of this battleship
Think of this, General Hatcher knew of these things, his Ordnance Department made about 150,000 of them for the Army, Army Air Corp, this is one type used in aircraft:
And Hatcher knew the things used greased ammunition! Yet Hatcher is running around claiming that greased or oiled ammunition dangerously increases bolt thrust. Is that not irrational? Hatcher knew, and yet, today's Hatcherites are militantly ignorant of these things. I believe it is due to their militant irrationality.
From reading Chinn's Machine Gun book series, post WW2 the Defense Department wanted to get rid of the grease out of the Oerlikon mechanism. The user had to pre grease cartridges, and that was time consuming and a mess, especially if dirt got on the cartridges. So post war testing consisted of a number of paths. One was fluted chambers, and I don't know why they did not pursue that avenue. Another was using teflon coatings on cartridges. The Navy test document I have says the highest rates of fire were obtained with oiled teflon coated cartridges. What the Navy/Air Force finally did, was to add an oiler to their Oerlikons, and that configuration was used up to the Vietnam War.
A Bullseye Pistol bud of mine was a more or less a river pirate in Vietnam. He and his Army Pirate buds were assigned duty on an armored barge and they got tired of accepting rounds from the local unfriendlies, so they stole an Oerlikon and crates of 20mm ammunition from an Air Force Base!. Once bolted to the deck of their armored barge, that Oerlikon helped them win hearts and minds. Bud said, they would go around the bend, take a round from a wooded area, and they would light up the whole damn area up with that Oerlikon. And after the barrage, all would be peace and quiet! His Oerlikon used an oiler.
The knowledge of this period is largely forgotten in the literature found in the in print community, and I believe it is deliberate, but then, it could be that the leaders of our society are not the experts they pretend to be.
