7.62 x 74.5 (30-06) Triplex


From left to right:
brass case, WRA 56
Brass csae, cannelure on neck, WRA 54

  1. The left one is a Triplex, isn’t it ?
  2. What is the right one ? A Duplex ?Why a cannelure ?



The one on the left is a triplex. These usually have a slight crimp at the base of the neck but sometimes this is hard to see. The one on the right is a duplex.

On the triplex the crimp is below the third bullet while on the duplex the crimp holds the second bullet. Since there is a special charge of powder BETWEEN the bullets to ensure dispersion, the crimp prevents the bullets from slipping down.


Very interesting, Chris.
Perhaps you can answer this question. Did the igniting powder being ground into the rifleing ahead of the rear bullets cause any undue barrel erosion? Did the forward powder even ignite before leaving the barrel?


Thank you very much Chris !