▁The ▁two ▁modified ▁weapons ▁were ▁designated ▁K 5 ▁Gl att . ▁ ▁Several ▁other ▁propos als ▁were ▁made ▁to ▁modify ▁or ▁create ▁new ▁models ▁of ▁the ▁K 5 ▁which ▁never ▁saw ▁production . ▁In ▁particular , ▁there ▁were ▁plans ▁for ▁a ▁model ▁which ▁could ▁leave ▁the ▁railway ▁by ▁use ▁of ▁spe cially ▁modified ▁T iger ▁II ▁tank ▁ch ass is ▁which ▁would ▁support ▁the ▁mount ing ▁box ▁in ▁much ▁the ▁same ▁manner ▁as ▁the ▁railway ▁weapon ' s ▁two ▁bog ies . ▁This ▁project ▁was ▁ended ▁by ▁the ▁defeat ▁of ▁Germany . ▁ ▁Project iles ▁Two ▁types ▁of ▁high ▁explos ive ▁project ile ▁were ▁used ▁with ▁the ▁K 5 . ▁The ▁ 2 8 cm ▁G 3 5 ▁we ighed ▁ ▁and ▁contained ▁a ▁charge ▁of ▁ ▁of ▁T NT . ▁The ▁ 2 8 cm ▁Gr . 3 9 ▁m . ▁H b gr . ▁Z . ▁was ▁slightly ▁heav ier , ▁we igh ing ▁ ▁and ▁containing ▁around ▁ ▁of ▁T NT . ▁ ▁These ▁project iles ▁were ▁pre - rif led ▁with ▁ang led ▁spl ines ▁along ▁their ▁mid section ▁which ▁were ▁aligned ▁with ▁the ▁guns ▁rif ling ▁before ▁firing . ▁ ▁The ▁ro cket ▁assist ed ▁project ile ▁was ▁known ▁as ▁the ▁ 2 8 cm ▁R . ▁GR . 4 3 5 1 . ▁This ▁carried ▁ ▁of ▁explos ive ▁and ▁was ▁boost ed ▁by ▁around ▁ ▁of ▁double - base ▁pow der ▁ro cket ▁prop ell ant . ▁The ▁total ▁weight ▁was ▁. ▁▁ 1 9 ▁seconds