Some general tweaking:

All Guns:
Recoil increased significantly across the board
Accuracy of most guns improved.
Diference between crouched and standing accuracy removed for all but the heaviest

guns (Snipers, M60, AM Rifle etc.) Crouching still greatly reduces recoil in all
cases.

SIG SG552:
Ammo reserve dropped to 360 (420 including a full mag)

Magnum:
Large Damage buff. Total DPS difference between Magnums and Pistols narrowed
significantly (Pistols are still better sustained, while magnums have burst)

Pistols:
Significantly more accurate when not firing
Considerably more affected by firing

Scar:
Mag size dropped to 40
Accuracy and recoil only slightly increased, Solidifying this gun's position as the
most accurate assault rifle. Reload speed changed to match the M-16's fast reload.

M-16:
Mag size dropped to 30.

Mil-Sniper:
Reload speed increased

Hunting Rifle:
Reload speed decreased

Minigun:
DPS increased. Should have little effect at long ranges, but upclose things should
get shredded in true minigun fashion.

Grenade Launcher:
Crosshairs have been narrowed significantly to make judging shots a little easier.
Still difficult though.

Recoil for automatic weapons increased slightly across the board

Reload times for assault rifles adjusted:
The SCAR, SIG and M-16 now reload 0.5 seconds faster

Magnum spread while moving reduced and recoil/Spread per shot increased to compensate.

Total number of Grenade Launcher shots reduced to 4 (1 Loaded with 3 in reserve)

Minigun spread reduced from 10 to 8

Been a while since the last update ^^

Just a very small change: The M-16's Clip Size has been increased to 40 to give it a stronger edge vs its other assault rifle counterparts.

Added LoadedAK47's Select Fire mod for semi-auto goodness.

Scout & Magnum
After much thought about the currently unsatisfactory (at-least in my opinion) position of these two weapons I have decided to massivly rework both of them.

Scout:
The Scout is now modeled after a single-shot pistol called the G2 Contender (Skin is now included in my CS Weapon Skin Pack (note the original skin is a AWP mod that I have hexed into being a Scout mod))
Now deals massive damage (enough to kill most non-boss special infected in a single shot)
Is considered a pistol and can be used while incapacitated (although you cannot zoom in.)
Despite it's huge per-shot damage, it's dps is extremely poor (160dps) and suffers from its slow fire rate vs common infected
However it has excellent penetration.

Magnum:
The Magnum has returned to a previous iteration of being a hammer-slapper (That is, a very high fire-rate revolver ;3)
As a result it's damage per shot has been reduced, but it's actual DPS has been increased
However it's sustained DPS is largely unaffected due to the low clipsize and reload speed.
Maintains it's status as the huge-burst-low-dps alternative to the low-burst-high-dps pistols (infact it now does it even better)
It's accuracy and spread-per-shot been increased and decreased respectfully to compensate for the increased fire-rate (the recoil is still a big problem for rapid fire accuracy though.)

Pump Shotgun:
Needs to be even less lethal to team-mates. Abandoning the huge pellet count idea as it has too many problems. -,o
Returned to 30 pellets and it's damage per shot reduced somewhat
To compensate it's spread has been tighened somewhat.

Silenced SMG:
Accuracy adjusted very slightly (Higher max inaccuracy, slower inaccuracy gain from shooting)
Recoil reduced slightly
DPS increased to 700

Pistols:
Damage per Shot increased to 50
Dual fire-rate cap reduced to 8 shots a second (Maintaining 400 DPS)
Should have better stopping power vs common infected

MP5:
Recoil greatly reduced
Reload duration reduced from 3 seconds to 2.25 seconds
Should be considerably more usable now

SCAR:
Clip-size increased to 60
This makes the SCAR have the second best sustained DPS out of the Assault rifles (beaten only by the SIG SG552 in full auto mode) but the worst burst.
Should also greatly improve usability

Shotguns:
The Combat Shotgun has had the width of it's spread increased, it's height decreased, and it's clip-size raised to 12 to further diversify it from the Tactical Shotgun as the go-to crowd-sweeper
The Pumpshotgun has been reworked... again. Due to problems with how Friendly Fire is calculated over multiple bullets, 135 bullets meant atleast 135 friendly fire...
Thus, the pumpshotgun now fires 80 pellets, and the size of it's spread drastically increased.
The damage per shot has been increased substantially to compensate.
Should emphasise the BOOM part of BOOMSTICK and reduce the chances of any premature friendly casualties.

Minigun & Heavy Machine Gun:
Rework of the mounted gun mechanics.
The Minigun now fires 100 rounds a second (from 25)
Minigun Spread increased greatly
Minigun DPS increased to 1000 from 800
Minigun cooldown time extended to 6 seconds from 3
Heavy Machine Gun fire rate increased to 20 Rounds a second (from 8)
Heavy Machine Gun DPS increased to 1000 from 400
Heavy Machine Gun Overheat time reduced to 10 seconds, while it's cooldown time has been reduced to 6 seconds
In general -
the Minigun is rather inaccurate but deals steady damage to everything you point it at. It has the longest fire-time before overheating It is the best mounted gun for dealing with Common Infected.
The Heavy Machine Gun is very accurate and deals massive damage even at extreme ranges, but lacks penetration or spread (a technical limitation I cannot change,) and has the shortest fire-time before overheating. It is the best mounted gun for dealing with Special Infected.

Survivors:
Melee weapons and the Chainsaw can now be used while downed.
Reload duration multiplier increased to double the normal reload duration while downed (from +50%)
Throwables are now usable while downed.
Crawl speed increased slightly (20 from 15.)

Correcting Addoninfo.txt.

This ain't no beta!

Pistols:
The Dual pistols are now capped at 10 shots a second (6 shots a second for a single pistol)
Damage per shot reduced to 40 (Maintaining 400 DPS)
Accuracy reduced across the board
Returned Clip-size to 20 per pistol

Magnum:
Fire-rate massively reduced to 2.5 shots a second
Damage per shot massively increased to 200 (DPS decreased to 400)
Accuracy improved, especially in a still crouch
Recoil increased slightly
Penetration greatly improved
Reload Speed decreased, Consider getting a Revolver mod for the Magnum.
The new reload speed looks weird with the default Magnum.

Scout:
Fire-Rate reduced slightly (1.25 shots a second from 1.333333)
Damage per shot greatly increased (240 from 200, 300 DPS at 1.25 shots a second)
Penetration improved significantly across the board

In general:
The differences between the Pistols and the Magnum should now be much more marked, with the Magnum being much more bursty and accurate while lacking total DPS,
While the Pistols have better sustained DPS, while lacking accuracy and burst damage. The Scout is now a little less flexible, but each shot is a little more potent.

General:
Ranges and penetration values for all weapons have been adjusted to better reflect reality.
In short: Shotguns have reduced range and penetration,
Rifles have increased range,
SMGs and Pistols now all have the same range and penetration (except for the Silenced SMG which has better penetration at close ranges for balance reasons)
Military Sniper Rifle Range and Penetration improved and the Hunting Rifle's penetration has been reduced to believable levels.
Maximum penetration distances and bullet ballistic curves at extreme ranges have also been adjusted to better reflect reality.

Another wide balance update. The focus this time is on refining rather than innovating however. Also, return of the Boom-Stick! (See the Pump-Shotgun changes)

Pistols:
Pistol Dual weild fire rate capped at 6.666666 shots a second while single pistol fire rate is capped at 5 shots a second.
DPS maintained at 450, resulting in much more damage per shot
Clip-size dropped to 10 per pistol, but reload duration massivly reduced (1 second from 1.75 for single pistols, 2 seconds from 3.5 for dual pistols)
Accuracy reduced across the board.
Penetration made less effective at range and limited to 250 units, but more effective at extreme close ranges.
Pistols should now finally be where I wanted them; as a the 'average,' 'jack-of-all-trades' secondary. Discovering I could actually change the reload speeds of the Dual and Single pistols individually let me subsistute a larger clip (which is too powerful) with a much faster reload (which is powerful, but not so much it becomes a better SMG...)
Pistols are now powerful burst damage weapons that lie between the Magnum and Silenced SMG in accuracy and raw DPS potential, providing a balance between the Silenced SMGs's destructive damage potential with the Magnum's decent range.

Magnum Pistol:
Magnum fire-rate capped at 4 shots a second (still higher than vanillas 3.333333 shots a second.)
DPS reduced to 350, however damage per shot remains practically the same.
Penetration adjusted to favour close range.
Accuracy while crouched decreased somewhat while accuracy while moving and standing improved greatly.
Recoil increased.
Still instagibs those fragile common infected making it the best horde clearing secondary at long range, but it's lower rate of fire and small clip means it struggles with the tougher infected. it's good accuracy means headshots are very viable however.

Shotguns:
Shotgun Accuracy reworked -
Shotguns with Wider Spreads are now less affected by moving and not affected at all by standing or crouching.
Shotguns with Tighter Spreads are much more affected by moving and standing, but have their maximum potential in a still crouch.
Wide Spread Shotguns now have 100 reserve ammo.
Tight Spread shotguns now have 120 reserve ammo.
Chrome-Shotgun DPS lowered to 400 from 415
The Pump-shotgun now uses number 4 Birdshot (135 pellets. No, it doesn't cause lag.) It's spread has been made significantly larger, but the huge pellet count guarentees damage at pretty much all ranges, although said damage is reduced exponentially by range. Theoretical damage per shot and DPS is unnaffected by this and penetration has been reduced to only extreme close ranges while recoil has been significantly increased. As an interesting side-effect, it also launches Special Infected if you kill them at point-blank range. Welcome to the new Boom-Stick :3
Generally speaking, 'Inaccurate' shotguns are more consistant in their accuracy no matter what you are doing, Do more with each shot but have less reserve Ammo
While 'Accurate' shotguns require you to be in a still crouch to get the most out of them and do less with each shot but have more reserve Ammo.
And every shotgun now uses a different kind of shot, making them more interesting to use.

Sniper Rifles:
Scout's DPS increased to 300 from 250, Penetration greatly improved at close ranges and clip-size returned to 10 from 11 (While the extra round is consistant with other weapon behaviours in the game... I just like even numbers. It looks better : P)
Hunting Rifle's Fire-rate increased slightly, and DPS increased to 380 from 350
Military sniper's Clip-size increased to 30 from 20 and DPS increased to 400 from 380, while it's penetration has been reduced at close ranges.
Primary Sniper rifle DPS is now a bit more competative with the other Primaries and the Scout's DPS is now barely passable. The Military sniper rifle is now more consistant with it's DPS due to the larger clip-size but not quite as devasatingly effective vs Common Infected at close range.

M60:
M60 accuracy adjusted to be somewhat less accurate while crouched (still very very accurate during semi-auto fire, but not perfect accuracy as it was before,)
while slightly more accurate while standing still and moving. Recoil increased somewhat.
Generally speaking, semi-auto fire while standing still is viable now, while full-auto is still suited to a still crouch. Also, no more sniper-rifle level accuracy (The M60 in real life is VERY accurate (a guy managed a world record long distance shot with it before after all) but the L4D2 version has no scope)

SMGs:
All SMGs have greatly improved Penetration at close ranges.
Silenced SMG returned to 600 DPS from 500 and it's reload duration reduced to 1.5 second from 1.75, while it's accuracy has been further worsened during full-auto, but improved during semi-auto. It's Penetration has also been adjusted to be less affected by range.
SMG max reserve ammo increased to 480 (2 extra mags)
SMGs should now have enough total ammo to tempt people into using them (especially the UZI) instead of a Tier 2 weapon in long maps requiring ammo conservation. The Silenced SMG should now also be good at killing commons again, and deadly at close range as intended.

Assault Rifles:
All Assault rifles now have greatly improved penetration at close ranges.
The M16's recoil has been reduced.
The M16 and SCAR-L Now have 360 from 300 reserve Ammo
The AK47 now has 270 from 300 Reserve Ammo
SIG SG552 now uses the new SMG reserve ammo cap (480 from 300, meaning The SIG has 9 mags total from 6)
In general a fairer amount of ammo for the least ammo efficient gun in the game and evens out the efficiency of the three other assault rifles. All assault rifles should now be able to perform for relativly equal amounts of time. Should also promote more use of the SIG's full-auto function.

Misc Changes:
The Pipebomb's Beeping now actually coinsides with the new timer duration.
Survivors now move a little bit faster while crouched. Now you move at 120 units per second from vanillas 85.

What was going to be a small update, kinda spiraled out of control...
Lots of new things and lots of balance changes:

Bugfixes:
Players can now actually move when spawning as an infected...

Grenade Launcher:
Explosion damage radius increased slightly
Damage against normal infected (and most importantly, Witches) increased to 3500. Tank damage remains the same.
While this weapon always fires at perfect accuracy, the crosshairs have been moved to sides to make judging your shots more difficult.
Total ammo reduced to 7

M60:
Fire-Rate reduced to 500RPM from 650RPM (depending on model, both can be true to reality)
Damage increased to 80 from 70 (666.666666 DPS. The same as the Grenade Launcher vs a Tank.)
Should make each shot provide more bang for it's buck, promoting usability.

Chainsaw:
Now has 150 Fuel (x5 that of Vanilla's 30)

Pistols & Magnum:
Fire rate for the single pistol capped at 6.666666 shots a second, 5 Shots a second for the Magnum Pistol and 10 shots a second for the Dual Pistols.
Magnum Damage reduced to 80 from 125 (400 DPS from 666.66666.) Will still insta-gib commons at all difficulties though. Just won't make quite as much a mess of tanks as it did before...
Magnum accuracy adjusted somewhat to favour a still crouch.
Pistol Damage reduced from 65 to 45 (450 DPS)
Pistol base accuracy adjusted to be generally less accurate but less affected by shooting and moving.
Pistol Penetration improved somewhat.
Pistol clip size increased to 20 (40 while dual wielding (obviously))

Unsilenced SMG:
Accuracy improved and Recoil significantly reduced.
Reload speed increased to 1.75 seconds from 2
DPS raised to 380 from 350

Silenced SMG:
Accuracy reduced significantly while still being reasonably accurate during burst-fire
DPS reduced to 500 from 600
Reload speed increased to 1.75 seconds from 2
Recoil increased slightly.
Changes should hopefully mean it won't be a better version of the SIG SG552...

Millitary Sniper:
Dps increased from 350 to 380

FN-SCAR:
I have finally figured out exactly how the Burst-Fire system for this weapon works!
The fire Rate can now finally be reduced to match reality without affecting it's DPS (God that was a pain to figure out...)
Accuracy improved and Recoil reduced very slightly
DPS raised to 425 from 400

M16:
DPS raised to 475 from 450

AK-47:
DPS raised to 500 from 475

MP5:
DPS raised to 430 from 400
Reload speed reduced to 3 seconds from 2

Chrome Shotgun:
Damage raised to 360 (theoretically) per shot
Spread increased somewhat to the same as the Tactical Auto-Shotgun
Penetration improved very slightly

Pump Shotgun:
Penetration improved to the same as the Combat Shotgun

Tactical Auto-Shotgun:
Pellets increased to 12 from 6. Same theoretical damage per shot.
Penetration improved to sit between the new Combat Shotgun and Chrome Shotgun

Combat Shotgun:
Penetration improved slightly

Bilebomb:
Zombies now deal 50 damage (from 10) to other infected affected by the bilebomb. Should now deal a significant amount of damage to a Tank and be a death sentence for any other infected apart from the witch.

Shotguns:
Reduced Close Range Damage Bonus to 2x (from x2.23) damage at 30 units (Half a metre) (from 50 units)
Damage to tanks has been reduced to around 500 DPS (x0.5 damage multiplier from x0.85) Untill you are close enough for the 2x damage bonus (at which point you have around 1000 DPS.)

Survivors:
Survivors can now Crawl very very slowly while incapped.
Changed the behaviour of Incapped attacks: Weapons now have their normal accuracy, but the 'dizzy' effect is much more intense while reload times have been increased and fire rate is capped at 2 shots a second.