The gyrojet, in all it's iterations, was just not useful on any level. Even today, man fired small weapons using rockets are not viable.

Until the payload is the size of something like the M72 or RPG/B40 or today's Carl Gustav.

1)expensive
2)inaccurate
3)prone to ignition failures

The Davy Crockett, was a complete failure for one reason. The crew, who served the weapon, were within the radius of the fall-out. This did not make the troops very happy.

Another failure, for the same reason was the 280mm atomic munitions fired from the M65 canon, nick-names Atomic Annie.

The only "small" atomic munitions that did have some usefulness was the US's back-packable SADM. Never employed, but it was deployed in several units in Europe during the 50t's thru the early 70t's. I never touched one, but had briefings and know several friends that actually were in units that had them as TO&E. The idea for the SADM was area denial. Explode one in an area to cause the East block advance to be rerouted around an area. Europe is full of train tracks that weave through the mountain valleys. The unit could be placed and the team would retreat to a "safe" area to detonate the munitions. (do google search)

My $00.00002