Just wondering:

When folk convert Brens to 7,62 x 54R, what (if anything) is done to allow for the significant difference in operating pressure?

The Russianicon cartridge is very close to the .30-06 in capacity and performance, thus, if an "original" barrel is simply reamed out for it, the port pressure will be higher than for the original .303. Let's also not forget that the .303 shoulder sits further forward than the 7.62.

So, what is the arrangement with your Bren?