The reason I think the way I do is because the booster pack only has 3 maps, and its called a booster pack, not an expansion pack. This is why I think it is just adding maps to the game, and that is why you cannot use those guns on regular maps, because they are only in those maps with those countries. SF was different because it was an expansion pack, it had more maps and the weapons were considered unlocks to regular BF2, so you could use them only if you have the original BF2 unlock.
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