[The Guns in Order and which Town to buy them from]

Pistols/Revolvers

Carver-MKI MP.100 BR [Can't Buy, Custom made]
Creek-Weeper-MKI MP.25 BR [Sable Creek]
Epsilon-MKIII MP.50 BR [Epsilon]

Rifle

Widowmaker-MKI MP.300 LDR [Goldengate/Gritrock/Wardengrass]

Shotguns

Gulch-Maker-MKV MP.250 SR

[The Round Types]

MP.25 BR
MP.50 BR
MP.100 BR

MP.150 LDR
MP.300 LDR
MP.500 LDR

MP.125 SR
MP.250 SR
MP.450 SR

BR stands for Basic Rounds [Used in Pistols/Revolvers]
LDR stands for Long Distance Rounds [Used in Rifles/Snipers]
SR stands for Spread Rounds [Used in Shotguns/Trench-Sweepers]