what is the difference between
Caliber Bullet Type Box of 50 Case of 1000
9mm 135gr Lead RN $10.99 $212.99
9mm 124gr TMJ $11.99 $229.99
9mm 124gr FMJ $13.49 $252.99
?
The two main differences are grain and bullet type.
Grain differences
135gr vs 124gr
Grain refers to weight when it is used to describe firearm ammunition.
Speaking in the broadest possible way, lighter bullets tend to be more accurate at short and medium range because they move faster coming out of the gun and have a flatter trajectory so it is easier to aim precisely. They tend to lose their speed relatively quickly, so they will also hit downrange targets with less force than heavier bullets.
Those heavier bullets are trickier to get precise shots at medium range, but air resistence will effect them less than their lighter brethren. They will retain more speed over longer distances, and so will hit distant targets with greater force.
Differences in bullet types
Lead RN = Lead RoundNose (uses a round nose lead bullet)
TMJ = total metal jacket (has copper around the whole bullet, it eliminates the amount of exposed lead that can be atomized at the moment of ignition and inhaled by the shooter, they usually use non-toxic, non-sulferic and non-lead primers, some indoor ranges prefer this ammo)
FMJ = full metal jacket (uses a soft core, usually lead, wrapped in a copper or steel-alloy)