Call of duty: Black ops for Playstation 3
Weapon upgrade list by Alex Watters (yet_another_demon | Hotmail UK)

This is a list i have compiled of all guns upgraded through the 'pack-a-punch' machine.
Hopefully it will give you an idea of which guns to upgrade.

Pistol - Mustang & sally (twin grenade launcher pistols)

M14 - minitia (Slightly more damage and 2 round burst)

Olympia - Hades (slightly more spread and damage)

Ak74 - AK74FU2 (more damage and grenade launcher)

MP4 - Afterburner (More damage)

Stakeout - Raid (more damage, larger clip and more spread)

MPL - MPL-LF (more damage)

Mp5K - MP115Kolider (slightly more damage)

PM63 - Tokyo & Rose (Twin SMGs with more damage)

M16 - SKullcrusher (Fully automatic and grenade launcher)

HK21 - H115 oscilator (Better damage and clip) best automatic

RPK - R115 resonator (better damage and clip)

M72 LAW (rocket) - M72 Anarchy (semi - automatic and larger clip)

China lake - China beach (larger clip, more damage)

CS75 - Calamity (Semi-automatic, better damage)

CS75 (dual wield) - Calamity and Jane (semi-automatic, better damage)

Python - Cobra (larger clip, better damage)

AUG - AUG-50M3 (larger clip, better damage and built-in shotgun)

Fn FAL - Epic Win (3 round burst, better damage, big scope)

Famas - G16-GL35 (better damage, funny smiley scope)

Commando - Predator (Better damage, larger clip)

G11 - G115 generator (better damage)

Galil - Lemantation (better damage, scope, larger clip)

Spas 12 - Spaz-24 (Better damage, larger clip, bigger spread)

Hs10 - Typhoid & Mary (better damage, twin shotguns, bigger spread)

Dragunov - D115 disassembler (better damage, zoom scope)

L96A1 - L115 isolator (better damage, zoom scope)

Ray gun - Porters X2 ray gun (better damage, larger clip)

Ballistic Knife - The Kraus Refribillator (Larger clip, bigger knifes)

crossbow explosive tip - Awful Lawton (Larger clip, More damage)

Thundergun - Zeuscannon (More damage, larger clip)

I would recomment the Zeuscannon, Porters X2 Ray gun and the H112 oscilator.