Duplex or triplex?


I have two cartridges of 30-06 multiball.

How knowledge if these are duplex or triplex ?

I observe a difference of weight of 12 grains :

  • Left cartridge (W C C 5 8) : 434.2 grains
  • Right cartridge (WRA 5 6) : 422.4 grains

The duplex use two projectiles of 96 grains (2x96=192), the triplex 3 projectiles of 60 grains (3x60=180) (“An Introduction to Collecting .30-06” article on IAA site).
One can deduct that the left cartridge is duplex and the right cartridge is triplex ?




Weighing standard case Project Salvo multiball rounds is NOT a foolproof way of determining if they are duplex or triplex. In theory, the duplex normally has two bullets of 95-96.5 grains (total projectile weight 190-193gr) while the triplex has three bullets of 59.5-60.5 grains (total projectile weight 178.5-181.5gr). So, IN THEORY, a triplex weighs LESS than a duplex. However, there is enough variation in the case, powder and bullets to give an overlap. Some Salvo rounds had a cup wad under the lower bullet, others had angled bases to the lower bullets to help dispersion. These all affected overall weight.
While the heavier round in your picture is likely a duplex the only foolproof way is to xray them.
(all bullet weights listed above taken from actual specimens)


Thank you for these precisions