Exploit, not a glitch or anything.
Ranger pack DLC is REQUIRED.
First off, when fighting the first
bandits with Bourbon, next to their
Campfire you will find a bunch of ammo
and more importantly a Volt Driver.
Pick up this volt driver now. When you
get to the Market, sell it for either
the Auto Shotty or the Thar with
Scope.Either works. Now, continue
playing until you find yourself in
Andrew the Blacksmith's room. On his
bed will be a Volt Driver, the Heavy
Auto Shotty and some Shotgun ammo.
Ignore these and go to the weapon
stall in the middle of the merchants.
Sell the Thar/Shotty for a DOUBLE
BARREL Shotgun. Then return to
Andrew's bed, pick up the Heavy
shotgun or the volt driver, whichever
you don't want, and return to the
merchant. Sell this weapon for ANOTHER
Double Barrel shotgun. Now, you can
either keep the remaining weapon for
your own personal use, or sell it for
yet ANOTHER Double Barrel shotgun. If
you do the latter, you can soon swap
out the double barrel for an
Automatic+Bayonet Shotgun in the Front
Lines. it's down a flight of stairs
near the Wounded tent behind Communist
front lines, on top of a pipe beside a
corpse. Now, continue through with
this until you are inside the station
past the Defense chapter. Up a flight
of stairs just on the inside of the
first radiation hotzone, to the left,
is a dead body with a Helsing, pick
that up and sell it once you've
delivered Sasha to safety, for another
Automatic Shotgun w/ Bayonet. Continue
playing until you reach the Black
Station, now. Inside of a bus near a
Patrol (somewhere close to the
Generator) you will find a Helsing.
Pick that up and keep it until you
reach Polis, where you can yet again
sell it for an Automatic Shotgun w/
Bayonet. Once through with the Library
you can pick a Volt Driver or Heavy
Automatic shotgun to actually play
with through the rest of the campaign,
as Polis was the last station with an
available trader and Ammo exchange
Kiosk. This little trick makes using
Ranger Hardcore mode unbelievably fun,
as you no longer run out of ammo
entirely, though still feel like its
rare.
Source