Actually, Dragon shows a pretty good and accurate distribution of weapons. In a US infantry fire team, there will be one LMG (M249 SAW) automatic rifleman, 2 M16A2 riflemen, and one M203 grenadeer. The idea for commonality of supply is the ammo. All the above weapons use the same basic ammo, 5.56mm, so supplying them isn't really an issue.
It is basically the same in the IDF para's. The FN is the only weapon that uses different ammo, 7.62mm. The other 3 weapons are all versions of the Galil 5.56mm rifle. They also throw in an RPG for good measure, which getting ammo for is like picking up leaves, no issues.
Same idea on the Khe Sanh USMC figures. During Vietnam, it was the same basic set-up. Just different weapons. The M79 was used as opposed to an M203, and the M60 was the predecessor to the M249, sort of. The automatic rifleman was originaly an M16 gunner with his weapon on full auto. It was found that this didn't provide enough firepower and wasted a lot of ammo. M60's were then attached to squads to give them more punch.
I could go on, but you get the idea, I hope. They are accurate. If you want the same weapons for all your figures, just swap out the weapons with some other figure sets or buy some weapons sets to swap them out with.
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