TheCannonballGuy said:I don't think it is an artillery projectile, because those don't have a threaded iron body. (I do see threading on it, not simple ridges/rings.) It could be the explosive head of a rocket or bazooka-round. Or it might not be a military item.
Precise measurements are needed.
Also, we need to see more photos -- particularly, close-up views of its base, and the front, to see if it has a fuzehole, which would be threaded.
The photo shows the large iron threading visible through the cracked outer casing of the rocket's fuel-section, below the explosive head. Unscrew the fuze in the nose, and that 2.75" rocket warhead would be a very close match to the Guam mystery-object. Not quite an exact match, but very close. The slight difference could be due to the Guam specimen presumably being from 1944, and the Cuddleback Lake Air Force Range specimen being from some decades later.