What was main gun on the M60's? 105mm's??
Right it was a 105mm which was still relatively new as some NCO preferred the 90mm because it had a completely mechanical firing pin vs the 105's electric charge in its firing pin.
The article explains this new round is simpler than the beehive and is only for relatively close ranges like the similar round the Sheridan tanks had. But the Sheridan's 152mm stubby big bore used flechettes instead of shot.