Confusion on Terminology
Over the long time of .303 mark VII production, a variety of Wads, Sealants, and assembly methods have been used, each noted in official texts correct for their time, but not to be taken as "Gospel" but rather a guide to the general progression of Ammo development.
Also, one must not take "Literally" some of the nomenclature, as meanings do (and have) changed over time. The use of "common" names, rather than the correct international chemical terminology is a constant source of confusion in old texts.
Names like "Swedish Pitch" ( ?made from retorting Pine stumps, or similar?) and "Russian Oil" ( from Baku, and suitable for immediate use as a lubricant in guns, just like "Rangoon Oil") are common in older texts...even the simple term "BeesWax" can mean different things to different people.
Getting back to the neck seal/lubricant question. Early (up to WW II) Mark VII projectiles(those with a low level cannellure for stab crimping) had a ring of Beeswax ( Cerum Apis melifera) applied; the sealant apllied over the wad (Paper card or "strawboard") was for waterproofing, and it was basically a compounded "mixture of Pitch,Wax and resins" which should solidify on drying, giving an impervious seal. It was applied by a mechanical "dropper" stick ( a "glob" of determined size/volume/weight sufficient to run up the sides of the bullet as the neck was formed around it.)
Of course, improper regulation of "glob" size could result in excess sealant going down through the wad and into the cordite. (Pressure of production, improperly trained "glob setters", too much solvent in the mixture...any number of variables.)
As ammo was made in ever larger quantities, (during WW II) the cost and availablility of a lot of the "ingredients" of this "bituminous" sealant ( term used adjectively, not specifically)
made manufacturers look for simpler and cheaper solutions. It was found that amongst other things, simple "Tar" ( or ashphalt or bitumen), either natural (Trinidad) or refinery derived, was good enough, if softened with a hydrocarbon solvent for ease of application.
This was used from the 1940s to end of production, and in some countries, carried over to 7,62 Nato production.
BTW, the ring of Beeswax was deleted in 1944-45, when the Stab crimp was deleted (replaced by the Mouth crimp, and shifting of the cannelure).
THis "Tarring and Waxing" was a typically British malaise, as European makers of .303 ammo ( all Granular Powder loaded) used either a simple neck lacquer (usually a "Duco" type nitrocellulose lacquer) or none at all. [ "Duco" was ( and is) a Dupont Trademark of Nitrocellulose based-Auto varnishes, made by dissolving NC in solvents, and applying it in many layers as a carbody finish...its level of "Nitration" was lower than that of NC Powders, so it was less "explosive"...also the other ingredients, such as Pigment etc, also reduced the flammability of the compound when dried...in Liquid form, it was just as combustible as normal Motor Fuel.
"Duco" == "Dupont Compound" varnish.
All of these "Sealants, Lubricants, etc" derived from a time when they were necessary for Black Powder loads ( Plain lead bullets, use in tropical climes, etc), and true to British Military tradition, they remained in place long after any real need for them actually existed, or after simpler and cheaper methods had been developed....
And to be a cause of great argument to the members of this board.
A lot of the supposedly "perceived" problems were just in the eyes of the observers, and did not affect battlefield reliability at all. As to the Browning MG problems, there could (were) be some problems, as the pressure development curves of Cordite are different from those of NC Powder, and that would affect the barrel recoil cycle, just as the "Port pressure" question affected where the Bren Gun eventually had its gas take-off hole. (Not that it eventually affected Bren performance with Nitrocellulose loaded ammo...Canada made millions (Billions) of rounds of Boxer 7z ammo during WW II, and continued using Berdan cases afterwards.(DIz, and 1950s DAC 7z).
WE do "Know" the following "facts" about Cordite vs. NC loaded ammo:
1. Cordite-fed barrels wear quicker and differently from NC-fed ones.
2. Cordite erosion was initially ascribed to "heat" and composition of original Cordite used;
a secondary cause, Ground Glass used in the priming Compound as a friction agent, was soon eliminated from priming compounds. Hence the development of the (Relatively) Cooler burning Cordite MDT.
This problem was still not eliminated, as shown by the tests with Cordite-loaded .276 Enfield P13 ammunition ( even more erosive that .303), and the WW II experience with Mark VIIIz ammo in Vickers Guns.
3. Wartime exigencies led to the change from "Glazed" carboard wad ( quite an involved manufacturing process) to simple and cheaper "Strawboard" wads ( using Wheat Straw, a relatively cheap material...an early form of "Green recycling", perhaps?)...
the same change was made from Aluminium nose plugs to Compressed Fibre ( less costly, I don't know what the "Fibre" was, probably some type of Wood or Cotton waste, compressed under heat and a binding agent, like hardwood "Masonite")...it is known that when WW I ended, they reverted to Aluminium plugs, but went to Fibre again in WW II...and remained so.
4. The Composition of the "sealant" changed with time and economies and place of manufacture. The various Publications give only a "Time Window" look at the situation as officially recorded. Confusion arises from our interpretation of the terminology used (Common terms against Trade and Scientific terms).
"ie, Resin, Bitumen,Ashphalt, Pitch" mean different things to different users, and to the general public; the Egyptian reference was to the result of 4,000 years of consolidation of the mixture of Natural Wood resins(saps), Mineral Bitumens ( out of "oil soaks") and Distillation products ( from tree stumps etc.) and other natural products, such as BeesWax ( the Bee was a Royal Symbol in Ancient Egypt, and a source of a large part of the medical cures of the time.
What was compared was the appearance of the dried resinous black mass found in Mummy wrappings with the compounds used for sealing not only ammunition from the rigours of a tropical climate.
5.A word to the Wise.... the problem is a Historical one....No one makes Cordite-loaded ammo any more, and existing stocks of pre-1970s Cordite loaded Mark VII will soon be exhausted by the insatiable US market. Any that is found is likely to be either "Dud" (primers failed) or "cracked" ( cases failed), or so old that our "Nanny State" Explosives regs prohibit the sale of it or import ( at least in Australia).
So by all means , have a well mannered debate on the why's and wherefore's of the Cordite question, but keep it Civil and Well Referenced..
BTW, my references are the direct examination of the cartridges themselves...the final arbiter of any question.... (Just like Gun variations...it is the item which defines the answer, not an old book or record, which is a (good) guide in most cases, and sometimes. unhappily, a red herring.).
Happy Shooting, Collecting, Reloading, etc.
And a Merry Festive season, whether it is Christmas, Hannukah, Festival of Lights, Eid, or Saturnalia...or just a rest from work....
See you all in the New Year, with new findings and disquisitions.....