TTT Pointshop Weapon Dropping!

[Mike Wazowski]

Hey Guys,
Basically i have added in pointshop to my server and in my weapons folder i have put in a weapon called the P228. When you buy it it gives you the weapon fine but if you already have a pistol it wont give you the p228 (p228 is a pistol) but will spend your points.
This is the normal working code:

TEM.Name = 'P228'
ITEM.Price = 3
ITEM.Model = 'models/weapons/w_pist_p228.mdl'
ITEM.WeaponClass = 'weapon_ttt_p228'
ITEM.SingleUse = true

function ITEM:OnBuy(ply)
	ply:Give(self.WeaponClass)
	ply:SelectWeapon(self.WeaponClass)
end

function ITEM:OnSell(ply)
	ply:StripWeapon(self.WeaponClass)
end

It works fine if u dont already have a weapon in that slot.
Im wanting to make it so when you buy a gun it will drop what ever gun is in that slot for example:
Deagle Is Equiped,When You Buy P228, Deagle Is Dropped, And P228 is Equiped.

i have attempted to do this by looking at other threads but no luck, Attempted Code Below:

TEM.Name = 'P228'
ITEM.Price = 3
ITEM.Model = 'models/weapons/w_pist_p228.mdl'
ITEM.WeaponClass = 'weapon_ttt_p228'
ITEM.SingleUse = true

function ITEM:OnBuy(ply)
	ply:DropWeapon(Weapon:GetSlot(1))
	ply:Give(self.WeaponClass)
	ply:SelectWeapon(self.WeaponClass)
end

function ITEM:OnSell(ply)
	ply:StripWeapon(self.WeaponClass)
end

Thanks For Helping.