Methods and gun for anchoring piles and for temporarily interconnecting two cylinders underwater

Methods and mechanisms for anchoring piles or offshore tower legs to the soil therearound and for joining two telescopic cylinders underwater in a temporary and inexpensive manner are disclosed. A gun fires projectiles radially from internally of the pile to form the plurality of outwardly extending anchoring bumps in the pile. After forming the bumps in the buried pile and simultaneously packing the soil around them, each projectile penetrates its bump and packed soil to provide a pile with increased load-carrying-capacity and with increased resistance-to-pull-out. Likewise, projectiles are fired in a horizontal plane radially outwardly and from within and normal to two telescopic cylinders underwater, for example, with two bumps being formed by each projectile, which bumps overlie each other tightly prior to their being penetrated by the projectile which holds the two bumps together. A number of radiating guns form a like number of pairs of bumps in a circle around the periphery of the telescopic cylinders to form an efficient, inexpensive, and simple temporary connection holding the two cylinders together.