Originally Posted by Ech0Sierra
YES, But no pistol grip.
You can build either a "featureless" build (no pistol grip, flash hider, etc.) that can have a detachable magazine, or a "fixed magazine" build which needs a pinned 10 (or less) round magazine, but can have a pistol grip and any other "evil" features.
The Bullet Button style magazine latch is a nice way to build a fixed magazine gun, but still be able to remove the magazine when necessary for maintenance, loading, clearing a jam, etc. Just make sure you never put in a magazine which holds more than 10 rounds.
If you want to be able to use larger magazines and/or drop magazines without using a tool, then you will need to use something like a MonsterMan grip in place of a pistol grip, and make sure that the build doesn't have any of the other banned "evil" features.