Shipping problems. (Call of Duty: Black Ops 2)

There is a question. I'm trying to earn all the medals from the "general" series. When a team member grabs a package you called. A common satellite, a common guardian, etc. Only warhog and lodstar remained. Hundreds of packages have been called. Perk engineer changed the content. As a result, from a serious 3 swarms, 1 dog, 2 VTOL aircraft, and the warhog and lodstar are like bewitched. On YouTube, there are a lot of videos with both in parcels. They write on the net that the chance of a swarm falling out is much lower than a warhog, but not for me. Tell me, maybe there is some kind of loophole that helps to increase the chance of a certain scorestreak falling out of the package?