Chamber shoulder and case shoulder gauge for .303?

[Parashooter]

Now on the "Reloaders Bench" forum there is a thread "Case head exits rifle" where Parashooter provided the following quite from Hatcher:
"If the bullet had been dipped in grease, this generally meant that the neck of the cartridge was greasy too. The space between the neck of the case and the neck of the chamber was filled with an incompressible substance, and the first moderate rise in pressure found it impossible to expand the neck and release the bullet. Thus the powder was strongly confined right at the beginning of its ignition, and accordingly the pressure rose disastrously."

Looks like you missed the text surrounding that quote from Hatcher -

I've noticed that many students of US military rifle lore think of the difficulties encountered with the 1921 "tin can" match ammo whenever lubricated cases are discussed. The actual problem with the 1921 ammo was not case lubricant but bullet lubricant inappropriately applied. To quote Hatcher, "If the bullet had been dipped in grease, this generally meant that the neck of the cartridge was greasy too. The space between the neck of the case and the neck of the chamber was filled with an incompressible substance, and the first moderate rise in pressure found it impossible to expand the neck and release the bullet. Thus the powder was strongly confined right at the beginning of its ignition, and accordingly the pressure rose disastrously." (Hatcher's Notebook, p 341).

As described by Hatcher, this problem was quite distinct from the added breech thrust occurring when the case body is lightly lubed. Although careless application of excessive case body lube could certainly have the same effect, such a result is easily avoided by applying only a very thin film.

The point of this post was to clarify that the pressure problems associated with greased bullets are the result of excess grease preventing the neck from expanding to release the bullet cleanly. This is very different from the added bolt thrust we get when lubricant on the case body reduces friction between case and chamber. NOT THE SAME THING! OK?

When contemplating the waxy lubricant band that used to be featured on Swiss 7.5 ammunition (GP11), don't overlook the fact that the Swiss chamber features an elongated neck designed to accommodate it.


Swiss 7.5 chamber neck is significantly longer than cartridge case, leaving room for lubricant formerly applied during manufacture.

There are practical and "approved" uses for lubed cases. Before the development of the fluted chamber (which allows powder gas to prevent adhesion of case to chamber), it was fairly common for automatic arms to employ lubricated cases or chambers. Most of these were MG's or LMG's, but two well-known shoulder rifles, the US Pedersen .276 and the Swedish AG42 Ljungman are documented as requiring lubricated cases for reliable functioning.

None of this means that lubing your .303 cases and firing them in your Lee-Enfield is a recommended practice. I've been doing it for years with no problems - but I'm a reasonably conservative handloader and my Lee-Enfields are all in sound condition. Some very good people think it's a terrible idea and will damage something sooner or later.

"Longitudinal and radial elongation play a role in creating the stress line that is a prominent feature in the typical Enfield head separations."

I believe those who assert that radial expansion contributes to the kind of head separation commonly encountered by .303 reloaders are mistaken. Radial expansion puts the circumference of the solid case web in shear, not stretch - and it does so in a completely different location. Failure in this manner is very uncommon with good modern brass and I've never seen an actual example, but here's a lousy picture from an old book that shows what occurs and where -