You're right - the .303 round was rimmed, so the Bren mag was curved, but the 7.62mm round is un-rimmed so the mag is straight.Wow! Great minds do think alike, I wanted the slightly curved 30 round magazine from an L4 LMG for my Falklands Paras SLR. I have seen photos of Paras with these magazines and I believe they modified them to fire full auto.
I think I am correct in saying the 7.62 mm LMG mags were different to the war time Bren mags.
Thanks mate. Chatted with TB yesterday re. the MKIII helmets I was chasing & the SLR/Bren mags.You're right - the .303 round was rimmed, so the Bren mag was curved, but the 7.62mm round is un-rimmed so the mag is straight.
Tony Barton had some white metal L4 mags a few years back - he may still have some so it's worth pinging him an email.