In Call of Duty: Modern Warfare 3 for the PC, PS3, Wii, and Xbox 360, you unlock the majority of the weapons in Survival Mode as you progress in levels. Most weapon groups have the same cost for each weapon in that group, with the exception of shotguns, which have a couple different costs.
Here is the full list of weapons in Survival Mode, how much they cost, and what level you unlock them at.
Assault Rifles – Cost $3,000 each
M4A1 – Unlocked by default
M16A4 – Unlocked by default (starting weapon on Tier 4 maps)
SCAR-L – Unlocked at level 5
ACR 6.8 – Unlocked at level 14
AK-47 – Unlocked at level 24
FAD – Unlocked at level 32
G36C – Unlocked at level 39
CM901 – Unlocked at level 43
MK14 – Unlocked at level 47
Type 95 – Unlocked at level 50
Handguns – Cost $250 each
Five Seven – Unlocked by default (starting weapon on Tier 1 maps)
USP. 45 – Unlocked by default (starting weapon on Tier 2 maps)
MP412 – Unlocked at level 2 (starting weapon on Tier 3 maps)
Desert Eagle – Unlocked at level 11
.44 Magnum – Unlocked at level 20
P99 – Unlocked at level 40
Light Machine Guns – Cost $7,000 each
M60E4 – Unlocked at level 12
PKP Pecheneg – Unlocked at level 18
MK46 – Unlocked at level 34
L86 LSW – Unlocked at level 41
MG36 – Unlocked at level 48
Machine Pistols – Cost $1,500 each
G18 – Unlocked by default
Skorpion – Unlocked at lvl 3
MP9 – Unlocked at lvl 17
FMG9 – Unlocked at lvl 37
Shotguns – Variable Costs
Model 1887 – $2,000, unlocked by default
USAS-12 – $2,000, unlocked at level 6
SPAS-12 – $2,000, unlocked at level 16
KSG-12 – $2,000, unlocked at level 26
Striker – $4,000, unlocked at level 33
AA-12 – $5,000, unlocked at level 44
Sniper Rifles – Cost $2,000 each
MSR – Unlocked at level 7
Dragunov – Unlocked at level 16
RSASS – Unlocked a level 29
L118A – Unlocked at level 35
AS50 – Unlocked at level 42
Barrett .50 Cal – Unlocked at level 49
Sub Machine Guns – Cost $2,000 each
MP5 – Unlocked by default
UMP45 – Unlocked at level 4
MP7 – Unlocked at level 13
PM-9 – Unlocked at level 23
PP90M1 – Unlocked at level 38
P90 – Unlocked at level 46
