Found this table in 2010 Annual Barrett magazine. Thought it would be interesting to share.
Designation: Tracer, M1
Purpose: Tracer round for incendiary purposes, target designation, observing fire and signaling
Tip Color: Red
Designation: Incendiary, M1
Purpose: Incendiary round for unarmored, flammable targets
Tip Color: Light Blue
Designation: Ball, M2
Purpose: Antipersonnel and unarmored target round
Tip Color: None - Brass
Designation: Armor-Piercing, M2
Purpose: AP round for light armored vehicles, protective structures, and personnel
Tip Color: Black
Designation: Armor-Piercing-Incendiary, M8
Purpose: AP Round for flammable light armored vehicles and armored targets
Tip Color: Silver
Designation: Tracer, M10
Purpose: Tracer round with M1 capabilities, but less intense
Tip Color: Orange
Designation: Tracer, M17
Purpose: Tracer round with M1 capabilites
Tip Color: Brown
Designation: Armor-Piercing-Incendiary, M20
Purpose: Same capabilites as M8 with tracer element
Tip Color: Red, with aluminum ring
Designation: Tracer, Headlight, M21
Purpose: Tracer round for air-to-air combat, three times brighter than M1 tracer
Tip Color: Dark Red
Designation: Incendiary, M23
Purpose: Incendiary round for unarmored, flammable targets
Tip Color: Blue with light blue ring
Designation: Ball, M33
Purpose: Improved antipersonnel and unarmored targets
Tip Color: None - Brass
Designation: Saboted Light Armor Penetrator, (SLAP) M903
Purpose: Utilizes plastic sabot containing small bullet for maximum penetration
Tip Color: Amber Plastic Sabot
Designation: Saboted Light Armor Penetrator Tracer, (SLAP-T) M903
Purpose: Similar to M903 with tracer element for target designation, observing fire, and incendiary purposes
Tip Color: Red Plastic Sabot
Designation: M1022 Long Range Sniper
Purpose: Highly accurate sniper round
Tip Color: Olive Green Bullet
Designation: Ball, XM1022
Purpose: Long-range match cartridge
Tip Color: N/A
Designation: Armor-Piercing-Incendiary, MK 211 Mod 0
Purpose: High Explosive Incendiary Armor Piercing (HEIAP) round with tungsten .30-caliber penetrator and explosive charge
Tip Color: Green Tip with Gray Ring
Designation: MK 257 Armor-Piercing-Incendiary Dim Tracer
Purpose: Tracer round visible only with Night Vision Goggles (NVGs)
Tip Color: Purple
Designation: Armor-Piercing-Incendiary Tracer, MK300 Mod 0
Purpose: Similar to MK 211 with a tracer component
Tip Color: N/A
Designation: Armor-Piercing-Explosive-Incendiary, APEI-169, M02
Purpose: Round for hard targets, lightly armored vehicles, ground threat suppression from aircraft guns or anti-aircraft platforms
Tip Color: Gray over Yellow
Designation: Tracer, M1
Purpose: Tracer round for incendiary purposes, target designation, observing fire and signaling
Tip Color: Red
Designation: Incendiary, M1
Purpose: Incendiary round for unarmored, flammable targets
Tip Color: Light Blue
Designation: Ball, M2
Purpose: Antipersonnel and unarmored target round
Tip Color: None - Brass
Designation: Armor-Piercing, M2
Purpose: AP round for light armored vehicles, protective structures, and personnel
Tip Color: Black
Designation: Armor-Piercing-Incendiary, M8
Purpose: AP Round for flammable light armored vehicles and armored targets
Tip Color: Silver
Designation: Tracer, M10
Purpose: Tracer round with M1 capabilities, but less intense
Tip Color: Orange
Designation: Tracer, M17
Purpose: Tracer round with M1 capabilites
Tip Color: Brown
Designation: Armor-Piercing-Incendiary, M20
Purpose: Same capabilites as M8 with tracer element
Tip Color: Red, with aluminum ring
Designation: Tracer, Headlight, M21
Purpose: Tracer round for air-to-air combat, three times brighter than M1 tracer
Tip Color: Dark Red
Designation: Incendiary, M23
Purpose: Incendiary round for unarmored, flammable targets
Tip Color: Blue with light blue ring
Designation: Ball, M33
Purpose: Improved antipersonnel and unarmored targets
Tip Color: None - Brass
Designation: Saboted Light Armor Penetrator, (SLAP) M903
Purpose: Utilizes plastic sabot containing small bullet for maximum penetration
Tip Color: Amber Plastic Sabot
Designation: Saboted Light Armor Penetrator Tracer, (SLAP-T) M903
Purpose: Similar to M903 with tracer element for target designation, observing fire, and incendiary purposes
Tip Color: Red Plastic Sabot
Designation: M1022 Long Range Sniper
Purpose: Highly accurate sniper round
Tip Color: Olive Green Bullet
Designation: Ball, XM1022
Purpose: Long-range match cartridge
Tip Color: N/A
Designation: Armor-Piercing-Incendiary, MK 211 Mod 0
Purpose: High Explosive Incendiary Armor Piercing (HEIAP) round with tungsten .30-caliber penetrator and explosive charge
Tip Color: Green Tip with Gray Ring
Designation: MK 257 Armor-Piercing-Incendiary Dim Tracer
Purpose: Tracer round visible only with Night Vision Goggles (NVGs)
Tip Color: Purple
Designation: Armor-Piercing-Incendiary Tracer, MK300 Mod 0
Purpose: Similar to MK 211 with a tracer component
Tip Color: N/A
Designation: Armor-Piercing-Explosive-Incendiary, APEI-169, M02
Purpose: Round for hard targets, lightly armored vehicles, ground threat suppression from aircraft guns or anti-aircraft platforms
Tip Color: Gray over Yellow