Armor
Armor is not converted directly from brand to game stats, like firearms.  The first thing GMs must determine is just how much of the body of the character is being covered by the armor.  Mere vests cover about 1/2 of a character's body, while flak-jackets with neck guards, crotch plates, leggings, and sleeves, covers more like 3/4 of a character.  Full assault gear covers as much as 9/10 of a character.  Armor in CoD acts just like Cover in D&D, covered on page 133 of the PHB, in respects to its bonuses to AC and Reflex saves.  Once all this is determined, the GM must decide what level of ammo is deflected by that armor.  Info on this can be gathered from many places, or just made up by the GM.

Once these stats have all been generated, the armor's Armor Check Penalty needs to be found.  This is best done by assigning a numerical value of 1 to 5 to all five of the different protective ratings, from E to A.  Armor greater than A cannot be worn.  Multiply this by the fraction of the character's body that is being covered, and round fractions to the nearest whole number.  This becomes that armor's Armor Check Penalty.  The armor's status as either light, medium, or heavy also needs to be determined.  Light armor has an Armor Check Penalty of 0-1, medium armor 2-3, and heavy armor 4-5.

As stated in the Converting Firearms section, if a character wearing Armor is fired upon by a weapon with a Penetration equal to or less than his Armor Rating, than the bullet doesn't go through his armor, and he may add his full cover bonus to his Defense score.  Otherwise, if the bullet has a higher penetration, than the armor's cover is treated merely as Concealment.  It still protects the wearer some, but the bullet can cut right through it if necessary.

Example: Josephine's character is a hardened female soldier of fortune in a WWIII type campain.  She wears a trusty old flak jacket, that's been through as many conflicts as she has.  The jacket has no crotch plate or arms, however, so the GM rules it covers 1/2 of the character's body.  It can protect up to .44 caliber bullets, or class B.  Josephine takes the 4 numerical level this Rating acqures, and multiplies it by 1/2, the amount of her body the armor covers.  Her flak jacket has an Armor Check Penalty of -2.

Explosives
Explosives are another thing difficult to transfer directly from real-world stats, since real-world stats are hard to find on explosives.  For the most part, the stats on explosives should be left up to the GM.  Remember, except in the case of directed explosives like door breaching charges, the more powerful the explosive, the larger the radius it affects.  The best way to model explosives is to look in the DMG for the object hardness and hit point chart, and then determine what you think your explosives (such as C-4) should be able to eat through.  All explosives do damage in d6 in their close radius, d4 in their far radius.  For every xd damage that your explosive does, give it a radius of about 2 feet.  Once you have the complete radius, divide it in two.  Anyone within the short range suffers xd6 damage, and may make a Reflex saving throw DC 20 for 1/2.  All those in the longer range suffer xd4 damage, and may make a Reflex saving throw DC 20 for 1/2 damage as well.  Note that anyone attempting a Reflex save in this situation is essentially diving down prone on the ground, unless they are behind some cover.  So their next turn, they need to spend a partial action getting up.  

For a general guide, we are going to give you stats for two common explosives: C-4 and a grenade.  C-4 comes in blocks of a fraction of a pound.  Every pound of C-4 does 12d6/12d4 damage, and has a radius of 12/12 feet.  However, since it is plastic explosives, it can be molded in particular shapes to carve shaped holes in walls, and this allows it to effectively reduce the radius to 5/5 feet.  Grenades do 6d6/6d4 damage, and have a radius of 6/6 feet.

Some explosives, namely Grenades, are fired from launchers.  Find the stats for the Grenade launcher, i.e. its brand and number of grenades held at once, and convert these into game stats.  It's not difficult, since grenade launchers are all assumed to have a base range of 10'.  Only one grenade may be fired per turn.

Firearms
Guns are converted according to their caliber.  Find the gun you are converting's caliber on the right side of the chart below, than scan left to find its base Penetration, Damage, and Recoil.  Note that some calibers are marked with an asterix.  This means that they are intended to be used in rifles.  If not used in rifles, than they act as if they were two Ratings lower, in terms of Rating, Damage, and Recoil.  Rating indicates the caliber's ability to penetrate armor.  Damage is, hopefully, self-explanatory.  Recoil is covered more below, and its affects are described in the section on Combat Rules.

Weapon Type- all modern firearms fall into groups, namely pistols, SMGs, rifles (automatic and single-shot), shotguns, and full machineguns.  Pistols include semi-automatics and revolvers, which fire single shots.  Any automatic pistol which fires bursts of bullets, or light ammunition automatic weapons are classified as SMGs.  Rifles are long weapons with a shoulder rest and long barrel, which can fire weapons in semi-automatic, bolt-lock, breech load, or automatic forms.  Shotguns are weapons that look like rifles, but fire much larger caliber bullets, frequently buckshot, and they can be semi-automatic, pump-action or automatic in form.  Full machineguns are the most powerful firearm, which fire bullets rapidly, at high speeds.  They can only be used held with major penalties, and are usually attached to vehicles, or mounted on bipods or tripods.

Mode- when researching your firearm, be sure to discover what modes it can function in.  Single-Shot mode (SS) is held by almost all weapons, except for Full Machineguns.  This means they fire a single shot with each pull of the trigger.  Other weapons are Automatic (A), meaning they fire continually while the trigger is held.  These are generally SMGs, some Rifles, and Full Machineguns.  Finally, a rare few weapons, generally SMGs, have a Burst mode (B), where they fire two to five bullets (usually a set amount) with every pull of the trigger.  Make a note of every mode of fire your weapon has.

Penetration- every weapon and caliber has a basic penetration, depending on its ammo type, and whether the weapon firing the bullet is a rifle.  Find the letter next to your weapon's ammo type.  If the weapon you are using is a pistol or SMG, than this is its base penetration.  Rifles have a penetration one level higher than normal.  Shotgun slugs have a penetration one level lower, and buck shot have an automatic D rating.  Full machineguns have a penetration two levels higher than normal.  When firing at a target wearing armor with an Armor Rating below your weapon's Penetration, than his armor doesn't count, because your bullet punches right through it.  Note that, after A, the ratings progress as E+, D+, C+ and so on, all the way to A++.  Note that any weapon or armor with a + rating automatically defeats weapon or armor without it.  The same goes for those with ++ and those with + or those with no +s.  Therefore, an E+ weapon defeats A armor.

Critical- all firearms, like all d20 weapons, have a crit range, which, if rolled within on an attack roll, results in a critical hit.  In CoD, damage from critical hits is applied directly to a target's Wound Points.  More on this is described in the Damage & Injury section.  Pistols and SMGs have a crit range of 19-20.  Rifles, Full Machineguns, and Shotguns firing slugs have a crit range of 18-20.  Shotguns firing buckshot do not get critical hits.

Damage- the most important aspect of a weapon, its Damage indicates how much injury that weapon can inflict.  Find the entry titled Base Dmg next to your ammo type.  This is a basic die type, indicated as 'dx' from here on out.  Pistols and submachineguns do damage equal to 2dx.  Rifles do damage equal to 3dx, as do full machineguns.  Shotguns do damage equal to 3dx if firing slugs.  If firing buckshot, they do 4dx damage within 10', 2dx damage between 10' and 30', and 1dx damage from there out to 60'.

Recoil- as well as Damage and Penetration, all weapons also have Recoil, which is a measure of the kick the weapon shoots back at the firer with each shot.  No weapon can ever have a recoil below one.  Pistols have the regular recoil listed next to their ammo type.  Rifles have a Recoil two higher, though it is frequently reduced by some of the below modifiers, namely the shoulder stock.  Shotguns have a Recoil two higher than normal, and Full Machineguns have a Recoil three higher than normal.  Recoil adjusts attempts to fire the weapon in question rapidly and accurately.  More on this can be found in the Combat section.  Many things can affect a weapon's Recoil when it is used, and these are described in the chart below.  Note that no weapon, no matter how adjusted, can have a recoil of less than one.

Range- another attribute of any firearm is its range.  This is the rate at which the weapon becomes less accurate.  Treat these ranges as is described in the PHB.  The range is 150' for automatic pistols and SMGs, 100' for revolvers, and 200' for other rifles and full machineguns.  Shotgun buckshot ranges are listed under the Damage section above.  Slugs have a base range of 200'.

Load- every weapon has a set number of bullets it can hold before it needs to be reloaded.  Call this its Load.  Weapons using cartridges take a partial action to reload, those without cartridges take a full action.  Loading a breech-loaded weapon is also a partial action.

Ammunition- your weapon's Ammunition is the basic item that you have used to determine the rest of its stats.  Record the type of Ammunition your weapon uses, so that you know if you can use ammo you might find in your weapon.  Note, also, that there are variations on some types of ammo, such as 7.62mmx39 and 7.62mm Type 68.  Ammunition of a different variation than a weapon normally takes cannot be used by it.  There are also special types of ammunition that affect some of your weapon's statistics, if you choose to use that ammo.  Most are made specifically for law enforcement or special-ops soldiers.  All are illegal to be held by civilians in most nations, except for rubber bullets and hollow points..  These are described in the chart below.

Example: Al's CIA special agent uses a highly specialized weapon, the Glock semi-automatic pistol.  The Glock 15 uses 9mm ammo, meaning it does a base 2d8 damage, has a penetration rating of C, and a base Recoil of 4.  As a semi-automatic gun, the Glock can only fire in Single-Shot mode.  The Glock holds 15 rounds without needing to be reloaded.  The website Al used as a reference describes the fact that the Glock is made out of a highly durable kind of ceramic, and therefore will not set off metal detectors (though its ammo will).  It also claims that it can fire underwater.  Al makes a note of this on his character sheet, along with the Glock's range of 150' as a semi-auto pistol.  Finally, he loads it with Frangible rounds, increasing the damage to 4d8, but reducing the Penetration rating to E.

Another Example: Joe's character is an expert counter-terrorist.  After referencing some books, Joe finds an entry he finds particularly appealling as a weapon: the MP-5 2000.  A submachine gun that fires 9mm ammo, the MP-5 has a base damage of 2d8, a Penetration of C and can hold 30 rounds without needing to be reloaded.  The MP-5 2000 can fire in Single-Shot and Automatic mode, as well as a three round Burst.  It also has an extendable stock, which may be put on or retracted as a partial action.  Finally, the gun has a base range of 150'.  The book indicates the MP-5 2000 has a special venting system that allows it to fire regular ammo as if it were firing sub-sonic ammo.  His GM rules that this is allowed in his campaign.  When fired without a stock, the gun has a base recoil of 4.  With the stock, this is effectively reduced to 2.  He loads it with Armor Piercing rounds, increasing the damage to 2d10, and the Penetration to A.  Also, because of his gun's special attributes, Joe's shots are all treated with an extra +5 to the DC to hear them.

Melee Weapons
In the modern era, melee weapons are not frequently used.  Swords and axes, for the most part, are rarely brought out onto the field of battle.  However, the statistics in the PHB can still be used for some of the modern weapons.  A rifle with a bayonet attached should be treated as a Half-Spear.  A bowie knife should be treated as a shortsword, but a Slashing weapon.  Brass knuckles are modern-day gauntlets.  Other modern weapons should also use the statistics of their medieval counterparts, as is demonstrated above.

Melee weapon proficiencies in the modern era are not taken as Simple, Martial, or Exotic.  Each is treated as an Exotic weapon, and requires its own proficiency.  Combat with melee weapons is treated just as in any other d20 game.  However, there is one difference.  As with all Call of Duty weapons, they can perform critical hits by rolling within the prescribed range, and deal damage directly to the target's Wound Points.  However, melee weapons still use their crit multipliers, with Firearms don't have, and multiply their crit damage by this, and than take it from their Wound Points.  A knife isn't necessarily a big risk in combat, unless they happen to hit you in the eye, or the chest.  This system reflects that.

Weapon Add-Ons
Finally, in the modern world, there are a number of add-ons available for weapons.  These create special affects for the weapon, and help it achieve certain goals.
Silencer- when paired with subsonic ammo this device reduces the ability to hear gun shots.  See the Listen skill under the Skills section.
Laser Targetting- a laser strapped onto a gun's barrel, this device greatly increases accuracy by illuminating where the bullet should hit the target.  Anyone using this device gains a +3 to aimed shots or aimed bursts.
Night Scope- important to soldiers acting at night, this allows characters taking aimed shots with rifles to look through a scope which increases light and makes it easier to see.  It reduces concealment penalties for darkness by two steps.  The same technology can be put into goggles or binoculars for characters.

The rules above are intended to be guidelines so that GMs and playes can use any type of weapon they wish.  However, we also realize that having a list of weapon stats could also be helpful.  We would greatly appreciate it if anyone who converts guns by the system above allows us to post their translations up here.  Please sned those, and other comments/questionts to our e-mail.