I came onto about 500+ 303 Brit cases, last weekend, cheap. So, what could I do but, buy them!

They are all Berdan primed so, I decided to change the primer pocket to a 209 shot gun primer and so far, it's working out. My test loads have been 200 gr cast bullet and 16.5 gr of Enforcer and no leakage, in a 1914 Enfield.

I have a 11" turret lathe and I made 25 cases this way, in about a hour, including setting it up, with the following tools:

#4 center drill (5/16")
Letter drill B (.238)
5/16" counter bore

I drilled the primer out, with the c'drill, to a depth that would leave a ~.015 chamfer on a B size drilled hole.

Came back with the B drill and drilled threw.

Then the 5/16" c'bore to a depth of .010 and it's finished.

First, the B drill cut to .239 and the basic size of the 209 primers, are .240.

The .010 is to seal the primer pocket,as that is the thickness of the 209 flange.

I have a decapper but, I need to make a recapper, probably out of a pair of pliers. 

I don't shoot much any more so, it will be a while, before I prove this out totally and go to full pressure GC cast bullet pressures but, so far, it does work at PB bullet pressures.

I though I'd post this because of the difficulty of finding brass these days.

It's not the first time I've done this, I used shortened, 7.65 x 54 Russian cases to make full dyl length, shot loads for my 45 LC's, in my Black Hawk and Red Hawk pistols and that worked out well.

Disclaimer:
If anyone tries this, please be careful to make sure the primer seals.I would make sure there is some interference fit in the primer hole and start with .005 c'bore or,less and increase it, until the breech block closes.

At one time I reloaded 7.5 Swiss rounds with Berdan primers using an RCBS decapping tool and Berdan primers sold by PMC.
I don't know if the tool or the primers are still available.

Steve.