sentences:  He designed the Danuvia 39M and improved it into the Danuvia 43M submachine gun.After he moved to the Dominican republic, he designed the .30 Kiraly-Cristobal carbine, which was essentially a copy of his earlier work, specifically the 44M (an improved 43M).He made two more Cristobal carbine versions, the delayed blowback M2 in .30 Carbine and the gas-operated M3 in 7.62×51mm NATO.