Someone from Call of Duty 5 Zombie Factory came in and said it was better to upgrade weapons.

A single person can get 4 guns by using the brush gun bug. It is suggested to upgrade M 19 1 1, Ruhr gun, stun gun and Thomson (in order to buy bullets).

There is no limit to how many people brush their guns, as long as you have money.

Generally speaking, the damage is slightly increased except that the bullet doubles to sound like a silencer and the flame trajectory turns red.

M 19 1 1 was upgraded to a Grenade.

After the electric cannon is upgraded, the magazine is 6/30 (seemingly) and the range is huge.

In addition to the above two kinds, other guns obviously have no special effect.

Power = lethality. The effect is obvious after upgrading. Later, in a magazine of MG24, you can't take down a zombie without a broken limb.