Skill magazine

General information
Skill magazines are special items unique to Fallout: New Vegas. They temporarily increase the player character's skills and abilities when used. By default, skill magazines provide a +10 increase to the respective skill (with the exception of True Police Stories, see below). With Comprehension, skill magazines provide a +20 increase. The effect lasts for 1 minute by default, 3 minutes with Retention. Logan's Loophole, by a quirk, causes skill magazine duration to double (2 minutes, 6 minutes with Retention). It is important to remember that they are not stackable, therefore using two magazines will not result in double the skill increase. Additionally, skill magazines will not take your skills past the normal maximum of 100.

Reading a skill magazine for a combat skill can be used to boost the damage of weapons. With a +10, this translates into an increase of 5% base weapon damage. With a +20, this translates into an increase of 10% base weapon damage. See individual weapon pages for specific information. As an example, +10 Energy Weapons with a Gauss rifle will result in an additional 6 damage per shot. A +20 results in an additional 12. Note that because weapons start off doing only 50% base damage (at skill 0), the actual relative % increase is much larger than 5 or 10%. Going from 10 to 30 Energy Weapons in the above Gauss rifle example is actually an 18% increase, for up to 6 minutes, non-addictively.

True Police Stories works differently from all other magazines in that it actually does not increase a specific skill. Instead, it increases your chance to critically hit with all weapons as if you had an additional +5 Luck (+10 with Comprehension). Depending on a weapon's critical multiplier, this can sometimes end up being quite a significant increase in chance to crit (and of course, True Police Stories will do nothing for a weapon that has a critical multiplier of 0).