303 British Chamber Diagram

[Bruce_in_Oz]

"Mil-Spec" .303 chambers are just weird.

From the very beginning to at least the No4 days, they were NOT cut using "modern-style", one-piece 'reamers.

They were cut using a series of odd little short reamers, one for each "feature" of the chamber. There was a =n associated set of gauges used to measure each different stage.

The best bit is that final "setting" of the chamber was achieved by firing a "special" cartridge closely related to a "proof' round, to settle the insides of the chamber AND "final seat" the barrel, bolt and body assembly. Remember that all of those Lee Enfields were made from various grades of metal ranging from glorified "mild steel" to malleable cast iron.

I will see if I can find the full description of the process in my tree-ware files.

Let's face it: NOBODY was expecting to be reloading the "once-fired" brass, especially on the two-way range. As long as the brass case sealed the pressure in the barrel and was then extracted in one piece, NOBODY cared.

And then, there are all the "surplus" rifles that have had their chambers"freshened-up" for commercial sale. On a rimmed case this is bad enough, but when you start seeing WW2 Mausers with a millimetre of headspace BEYOND the "No Go' gauge, sphincters start to twitch.

The past is an "interesting" place.