On page 2 of lube formulas..SPG cautions against using tallow that hasn't been purged of salt as a lube ingredient.  Back in the 1990's, I had a write up in the CBA Journal about salt in tallow...repeated melting in pure distilled water didn't completly remove all traces of salt.  How would one completly purge tallow of salt?  At the time of article, I was mainly concerned with tallow in smokeless loads..which are not normally cleaned with a water-based cleaner.  I have been mixing up some experimental batches of B.P. lube using mutton tallow rendered from kidney fat..along with Beeswax, Baywax, castor oil & Lanolin.  If cleaning after use of B.P. with a water-based solvent..is there any concern of salt in the tallow?  Thanks.

Tallow is a generic name for rendered animal fat.  It can be made from many kinds of fat and subject to processing that varies from home stove top to industrial .

You should assume it does have some salt content unless proven otherwise.  We used to load Tallow out of rail tank cars into ships deep tanks for export. My area it all came from pork and poultry plants. 

We kept one quart sample jars to determine quality as loaded in case of a claim. After the ship discharged no claim thrown away. Kept a lot of it for home shop jobs, bullet lube and any place you would use grease .  One jar I painted on boat trailer axle and springs, rusted them up in short order. Local chemist that did a lot of cargo testing work gave me the scoop and offered to test any I wanted to use for gun work. Was amazed how much it varied . Did not charge me for the test, if you had to pay it would be cost prohibitive

Boats

You are technically correct, but all rendered animal fat is commonly called tallow. One of the reasons we kept samples was potential claims over grades and sources. Export documents, letters of credit all called it tallow and refrenced the sample held by independent chemist .  Customs duties commonly varry according to the type so it needs to be specifically identified . When I worked in Australia all the tallow we loaded was mutton or beef origin.

Point being unless you have analysis the home lube maker really has no idea what the salt content is. Even knowing the source the home render methods can't guarantee purity.

As a side note we still load a lot of tallow . Now in intermodal ISO Tank containers, moved on pure container ships. Shipper loads at his facility reciever unloads at his. We don't touch the cargo, just the container and don't pay claims. My source of good stuff is gone.

Boats

All animals like salt licks, and hunting around a salt lick is an old trick to improve your chances for success, and it's funny what animals you'll see licking salt blocks placed out in a field.
Animals (including humans) require a certain amount of salt.

I would not worry about tallow with slight salt content in BP lubes. Well cleaned with water after shooting, cleaned again next day, then oiled will preserve the bore. 

Smokeless powder cleaned with oil only don't think I would use it.

That's just me, someone else may see it different.

Boats

Eric, that's high-ish friction. Not high pressure. 
As to Unique in bullet lube, you may look up the MSDS on the internet and find if there are any promising ingredients in it for your use. 
It is, far and away my favorite case lube- and for that it's real cheap!