What common calibres are in the UK?

[CharlesHarris]

Shotgun powders of the type normally used for 12-ga. target and light field loads, typically 32 grams of shot at 350 m/s, are very suitable for pistol and revolver calibers, such as the .32 S&W Long, .38 Special or .45 ACP, or light small game loads in in center-fire calibers, such as the 5.56, 7.62x39, .303, 7.62 NATO, .30'06, 8mm, etc. When using the fast shotgun powders loads must be kept mild, and great caution is required to determine the proper charge and to visually inspect every case with a small penlight to ensure correct powder fill, to avoid any accidental double- or spilled charges.

The key in such loading in a SHTF situation is to be frugal, and to select a charge which reliably gets the bullet out of the barrel, with good ballistic uniformity, but in which an inadvertent double charge WILL NOT BLOW UP THE GUN!!!!

My boyhood mentors developed such loading techniques in the US during the Depression years of the 1930s, continuing in their use through the War years, in which sporting ammunition was simply unavailable and you had to "make do." Years later when visiting in Italy, my hosts indicated that this had been common practice among peasant farmers since the days of Garibaldi!

Using the common 12-ga. powder charge, as the baseline, being that powder was salvaged from misfired or swollen shotgun cartridges or swollen booster cartridges from Stokes 60mm or 81mm mortar rounds which had gotten wet...

A typical 12-ga. charge in old fashioned paper shells with fiber wads was 1.5 grams of a powder similar to US Red Dot, Green Dot, 700X. In modern plastic shells with plastic wads, a more typical charge is 1.2-1.3 grams. Not that you would have any to salvage, but my Italian friends tell me that the US 60mm mortar the WW2 booster shell typically contained 2g of slower, double-based powder, which worked wonderfully! [called Infallible] which is similar in burning rate to modern shotshell powders Unique, PB, or WSF.

The Italians have determined charges by empirical testing, using a chronograph and LONG string tied to the trigger, and offer the following guidelines for the next generation of Contadini Partizans:

Small game charges using cast bullets of wheelweight metal of standard weight for the caliber:

In 5.56, .38 Special and .45 ACP use 1/5 of the 12-ga. load,
In the 7.62x39, .45 Colt or .44 Magnum use 1/4 of the 12-ga. load,
In the .303, 7.62 NATO, 8mm, 7.62x54R Russian and .30-'06 1/2 of the 12-ga. load.

To reload for their common 11mm black powder cartridge rifles, the centre of the fired Berdan primer cup is drilled through the firing pin indent entirely solid web of the case using a 94 Gage (.18mm) drill. Then the hole in the primer cup is enlarged with a 6 gage (5.2mm) drill, taking care to not remove metal in the web of the case, other than to remove any residuals remaining of the Berdan primer "anvil" formed in the case head.

If you drill too far, take the 6 gage drill entirely through the web of the case, and the cases may still be reloaded with black powder, using 209 size shotshell primers, after lightly chamfering the edges of the hold with a 10mm drill bit. They then reload the brass with cast lead bullets lubricated with tallow and use a smokeless powder igniter equal to the .38 Special or .45 ACP charge, to reduce fouling, then fill the case the rest of the way with black powder. Brass cases fired with black powder are dropped into a jar with a 50-50 of white vinegar and water as they are fired. Upon arrival home the fired cases are decapped with an icepick, then washed again in hot water with a mild detergent, then again in clean water and left to dry.