Complete guide.

Step 1: Enter a game, any map and game type, just make sure you give yourself enough time.
*Its best (recommended) to do this in adhoc.*

Step 2: Do an exact search. Search 0x43340000. This is is the last value of the 20 line subs.

Step 3: Now you should come across 26 matches. Disregard all except the ones labeled 0x00F?????. All 0x000F's are each weapon for that map. With the weapon values below, you can find what gun your looking for. If you have a problem doing so, simply search the weapon value, and you should find only 3 0x000F's now. Its the one with 0x4334 at the bottom of the sub.
[Middle one]

Step 4. Once you found the correct sub, its all about mixing and matching or moding. Refer to the information below to guide what is what:

20 Line sub dynamics:
From the the weapon values to 0x43340000
Line 1: Weapon value
Line 2: Weapon Speed <---modify via different gun's speed values
Line 6: Bullet Type <-----modify via different bullet from another gun
Line 15 : Bullet Sound <----modify via 000100??
Line 17: Amount of bullets/shots fired <---modify via 000?000? (Don't go too high)
Line 18: Ammo <---modify
Line 19: Rapid Fire <----modify
Line 20: End sub with 0x43340000

The rest is unknown or has no effect.

Here are the weapon values you should be looking for:

SHOTGUN
0x3D07D75C

M1 GRAND
0x9B42A47B

KARABINER
0x668B0716

BAR
0x1AA20FE4

STG44
0x5D2EC45C

THOMPSON
0xAD8567E5

MP40
0x884F2C3D

GEWHER RIFLE
0xBBBD860C

SPRINGFEILD
0xCAE6F38C

P. BAZOOKA
0x496337DE

M1 BAZOOKA
0x496D946C

Please enjoy this relatively easy guide.