Originally Posted by
Dallas Frohrib
Dallas Frohrib, CherryBalmz – So, in regards to AR-15 lubrication, you hear a lot of people say ARs like to run wet, right?
They’re more lube sensitive than most because the DI system is pumping a lot of gas into that action area where the lube is.
The thing is, when we started running the numbers, DI guns were simply burning off oils a lot faster than they should have been.
CLP, motor oil, whatever…We knew we were missing something, as the heat and volume of the gas just couldn’t account for the amount of burn-off that was occurring.
When we dug into it, the fouling that all of us have been calling “carbon” for so long?
Well, it turns out there’s almost zero carbon in combustion fouling at all.
It’s about 98 percent lead and copper particulate, coming out in rough sphericule shapes between .5 micron and 10 micron, with the final two percent being things like tin, antimony, or steel, depending on the composition of the cartridge.
In rifles you’re looking at a 70/30 copper-to-lead ratio, and in pistols it’s flipped, at 30 percent copper, 70 percent lead.
But yeah, almost all the carbon in the powder is converted to gasses, like CO2.
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So it’s this super-heated, dense metal particulate that was causing so much of the AR-15 lubrication burn-off in DI ARs, and suppressed guns.
The temperatures inside a cartridge at ignition are right around 5,000 degrees Fahrenheit for a microsecond, and go down to about 3,000 degrees Fahrenheit two to six inches from the chamber.
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These temperatures atomize these different metals, and under these extreme pressures in the bore they start getting recombined into this spherical particulate, but it’s the density of these metals that allows them to retain such extreme heat for far longer than the gasses they’re carried in.
And that’s the key friction challenge you find in DI ARs, and suppressed guns.
The friction of the particulate itself, and how rapidly it polymerizes or burns off most lubes.
It’s also why the cam pin and cam channel are the most under-appreciated friction surfaces in an AR.
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