How many rounds can a typical M27 or M16-series magazine legally hold in practice on the range, and what is the risk of overloading?

• A. 30 rounds; overloading can cause feed malfunctions and increased stress on the follower and springs.
• B. 50 rounds; overload improves feed.
• C. 20 rounds; overload has no effect.
• D. 10 rounds; overload reduces stress.

Answer: (D)

The rounds per magazine for M27 and M16-series mags are set by the magazine design to 30. That 30-round capacity is the practical, intended limit for reliable feeding on the range. If you try to overfill a magazine, the extra rounds press against the feed lips and create abnormal spring compression. This increases wear on the follower and springs and can cause feeding problems—such as misfeeds, jams, or bolt not fully chambering—because the rounds aren’t presented to the bolt exactly as the system was designed to cycle. So, the safest, most reliable practice is to load up to the magazine’s designed capacity (about 30 rounds) and avoid overloading, which degrades feed reliability and accelerates wear.