No, the items you get out of the various packs that are available is dependent on the pack you're purchasing. Within each level of pack you will get a specified chance at various items, in the higher packs you also get the opportunity to get Rare and Ultra Rare items. The drop rates per pack are detailed in this question.
Keep in mind that weapons have a maximum level - once you get them to level 10 you'll stop seeing them appear in the packs!
I have only included the rarity name (ie: common) in the tables below for space purposes. For the rarity of each weapon, look at this list:
Assault Rifles
Common Uncommon Rare Ultra Rare
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M-8 Avenger M-15 Vindicator Geth Pulse Rifle M-99 Saber
M-96 Mattock Collector Rifle Cerberus Harrier
Phaeston M-37 Falcon Particle Rifle
Striker Assault Rifle N7 Typhoon
M-55 Argus N7 Valkyrie
Adas Anti-Synthetic Geth Spitfire
M-7 Lancer
Heavy Pistols
Common Uncommon Rare Ultra Rare
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M-3 Predator M-5 Phalanx Arc Pistol M-77 Paladin
M-6 Carnifex Scorpion
Acolyte M-358 Talon
Executioner Pistol N7 Eagle
M-11 Suppressor
Shotguns
Common Uncommon Rare Ultra Rare
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M-23 Katana M-22 Eviscerator Disciple M-11 Wraith
M-27 Scimitar Geth Plasma Shotgun N7 Crusader
Graal Spike Thrower Venom Shotgun
M-300 Claymore
Reegar Carbine
N7 Piranha
AT-12 Raider
Sniper Rifles
Common Uncommon Rare Ultra Rare
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M-92 Mantis M-13 Raptor M-98 Widow Black Widow
M-29 Incisor Kishock Harpoon Gun Javelin
M-97 Viper Krysae Sniper Rifle M-90 Indra
Collector Sniper Rifle N7 Valiant
Submachine Guns
Common Uncommon Rare Ultra Rare
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M-4 Shuriken M-12 Locust M-25 Hornet N7 Hurricane
M-9 Tempest Geth Plasma SMG Collector SMG
Blood Pack Punisher
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